--- loncom/interface/statistics/lonproblemstatistics.pm	2003/03/26 16:26:35	1.43
+++ loncom/interface/statistics/lonproblemstatistics.pm	2008/10/23 09:07:51	1.114
@@ -1,6 +1,6 @@
 # The LearningOnline Network with CAPA
 #
-# $Id: lonproblemstatistics.pm,v 1.43 2003/03/26 16:26:35 matthew Exp $
+# $Id: lonproblemstatistics.pm,v 1.114 2008/10/23 09:07:51 bisitz Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -26,367 +26,1478 @@
 #
 # (Navigate problems for statistical reports
 #
-###
+###############################################
+###############################################
+
+=pod
+
+=head1 NAME
+
+lonproblemstatistics
+
+=head1 SYNOPSIS
+
+Routines to present problem statistics to instructors via tables,
+Excel files, and plots.
+
+=over 4
+
+=cut
+
+###############################################
+###############################################
 
 package Apache::lonproblemstatistics;
 
 use strict;
-use Apache::lonnet();
+use Apache::lonnet;
+use Apache::loncommon();
 use Apache::lonhtmlcommon;
 use Apache::loncoursedata;
 use Apache::lonstatistics;
+use LONCAPA::lonmetadata();
+use Apache::lonlocal;
+use Spreadsheet::WriteExcel;
+use Apache::lonstathelpers();
+use Time::HiRes;
+use LONCAPA;
+ 
+
+my @StatsArray;
+my %SeqStat;    # keys are symbs, values are hash refs
+
+##
+## Localization notes:
+##
+## in @Fields[0]->{'long_title'} is placed in Excel files and is used as the
+## header for plots created with Graph.pm, both of which more than likely do
+## not support localization.
+##
+#
+#
+##
+## Description of Field attributes
+##
+## Attribute     Required   Value       Meaning or Use
+##
+## name            yes      any scalar  Used to uniquely identify field
+## title           yes      any scalar  This is what the user sees to identify
+##                                      the field.  Passed through &mt().
+## long_title      yes      any scalar  Used as graph heading and in excel
+##                                      output.  NOT translated
+## align           no    (left|right|center)  HTML cell contents alignment
+## color           yes      html color  HTML cell background color
+##                                      used to visually group statistics
+## special         no          (link)   Indicates a link, target is name.link
+##                                      Currently set in &get_statistics()
+## graphable       no      (yes|no)     Can a bar graph of the field be 
+##                                      produced?
+## sortable        no      (yes|no)     Should a sort link be put in the
+##                                      column header?
+## selectable      yes     (yes|no)     Can the column be removed from the
+##                                      statistics display?
+## selected        yes     (yes|no)     Is the column selected by default?
+##
+## format          no      sprintf format string
+##
+## excel_format    no      excel format type 
+##                               (see &Apache::loncommon::define_excel_formats
+my @Fields = (
+           { name => 'problem_num',
+             title => 'P#',
+             align => 'right',
+             color => '#FFFFE6',
+             selectable => 'no',
+             defaultselected => 'yes',
+           },
+           { name   => 'container',
+             title  => 'Sequence or Folder',
+             align  => 'left',
+             color  => '#FFFFE6',
+             sortable => 'yes',
+             selectable => 'no',
+             defaultselected => 'yes',
+           },
+           { name   => 'title',
+             title  => 'Title',
+             align  => 'left',
+             color  => '#FFFFE6',
+             special  => 'link',
+             sortable => 'yes', 
+             selectable => 'no',
+             defaultselected => 'yes',
+           },
+           { name   => 'part', 
+             title  => 'Part',
+             align  => 'left',
+             color  => '#FFFFE6',
+             selectable => 'no',
+             defaultselected => 'yes',
+           },
+           { name   => 'num_students',
+             title  => '#Stdnts',
+             align  => 'right',
+             color  => '#EEFFCC',
+             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Number of Students Attempting Problem',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'tries',
+             title  => 'Tries',
+             align  => 'right',
+             color  => '#EEFFCC',
+             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Total Number of Tries',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'max_tries',
+             title  => 'Max Tries',
+             align  => 'right',
+             color  => '#DDFFFF',
+             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Maximum Number of Tries',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'min_tries',
+             title  => 'Min Tries',
+             align  => 'right',
+             color  => '#DDFFFF',
+             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Minumum Number of Tries',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'mean_tries',
+             title  => 'Mean Tries',
+             align  => 'right',
+             color  => '#DDFFFF',
+             format => '%5.2f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Average Number of Tries',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'std_tries',
+             title  => 'S.D. tries',
+             align  => 'right',
+             color  => '#DDFFFF',
+             format => '%5.2f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Standard Deviation of Number of Tries',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'skew_tries',
+             title  => 'Skew Tries',
+             align  => 'right',
+             color  => '#DDFFFF',
+             format => '%5.2f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Skew of Number of Tries',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'num_solved',
+             title  => '#YES',
+             align  => 'right',
+             color  => '#FFDDDD',
+             format => '%4.1f',#             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Number of Students able to Solve',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'num_override',
+             title  => '#yes',
+             align  => 'right',
+             color  => '#FFDDDD',
+             format => '%4.1f',#             format => '%d',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Number of Students given Override',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'tries_per_correct',
+             title  => 'tries/correct',
+             align  => 'right',
+             color  => '#FFDDDD',
+             format => '%4.1f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Tries per Correct Answer',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'num_wrong',
+             title  => '#Wrng',
+             align  => 'right',
+             color  => '#FFDDDD',
+             format => '%4.1f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Number of students whose final answer is wrong',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'per_wrong',
+             title  => '%Wrng',
+             align  => 'right',
+             color  => '#FFDDDD',
+             format => '%4.1f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Percent of students whose final answer is wrong',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'deg_of_diff',
+             title  => 'DoDiff',
+             align  => 'right',
+             color  => '#FFFFE6',
+             format => '%5.2f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Degree of Difficulty'.
+                           '[ 1 - ((#YES+#yes) / Tries) ]',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+           { name   => 'deg_of_disc',
+             title  => 'DoDisc',
+             align  => 'right',
+             color  => '#FFFFE6',
+             format => '%4.2f',
+             sortable  => 'yes',
+             graphable => 'yes',
+             long_title => 'Degree of Discrimination',
+             selectable => 'yes',
+             defaultselected => 'yes',
+           },
+##   duedate included for research purposes.  Commented out most of the time.
+#           { name => 'duedate',
+#             title => 'Due Date',
+#             align => 'left',
+#             color => '#FFFFFF',
+#             sortable => 'yes',
+#             graphable => 'no',
+#             long_title => 'Due date of resource for instructor',
+#             selectable => 'no',
+#             defaultselected => 'yes',
+#            },
+##   opendate included for research purposes.  Commented out most of the time.
+#           { name => 'opendate',
+#             title => 'Open Date',
+#             align => 'left',
+#             color => '#FFFFFF',
+#             sortable => 'yes',
+#             graphable => 'no',
+#             long_title => 'date resource became answerable',
+#             selectable => 'no',
+#             defaultselected => 'yes',
+#            },
+##   symb included for research purposes.  Commented out most of the time.
+#           { name => 'symb',
+#             title => 'Symb',
+#             align => 'left',
+#             color => '#FFFFFF',
+#             sortable => 'yes',
+#             graphable => 'no',
+#             long_title => 'Unique LON-CAPA identifier for problem',
+#             selectable => 'no',
+#             defaultselected => 'yes',
+#            },
+##   resptypes included for research purposes.  Commented out most of the time.
+#           { name => 'resptypes',
+#             title => 'Response Types',
+#             align => 'left',
+#             color => '#FFFFFF',
+#             sortable => 'no',
+#             graphable => 'no',
+#             long_title => 'Response Types used in this problem',
+#             selectable => 'no',
+#             defaultselected => 'yes',
+#            },
+##   maxtries included for research purposes.  Commented out most of the time.
+#           { name => 'maxtries',
+#             title => 'Maxtries',
+#             align => 'left',
+#             color => '#FFFFFF',
+#             sortable => 'no',
+#             graphable => 'no',
+#             long_title => 'Maximum number of tries',
+#             selectable => 'no',
+#             defaultselected => 'yes',
+#            },
+##   hinttries included for research purposes.  Commented out most of the time.
+#           { name => 'hinttries',
+#             title => 'hinttries',
+#             align => 'left',
+#             color => '#FFFFFF',
+#             sortable => 'no',
+#             graphable => 'no',
+#             long_title => 'Number of tries before a hint appears',
+#             selectable => 'no',
+#             defaultselected => 'yes',
+#            },
+#
+##   problem weight for instructor
+           { name => 'weight',
+             title => 'weight',
+             align => 'right',
+             color => '#FFFFFF',
+             sortable => 'no',
+             graphable => 'no',
+             long_title => 'Problem weight (for instructor)',
+             selectable => 'yes',
+             defaultselected => 'yes',
+            },
+);
+
+my @SeqFields = (
+           { name   => 'title',
+             title  => 'Sequence',
+             align  => 'left',
+             color  => '#FFFFE6',
+             special  => 'no',
+             sortable => 'no', 
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'items',
+             title  => '#Items',
+             align  => 'right',
+             color  => '#FFFFE6',
+             format => '%4d',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'Number of Items in Sequence',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'scoremean',
+             title  => 'Score Mean',
+             align  => 'right',
+             color  => '#FFFFE6',
+             format => '%4.2f',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'Mean Sequence Score',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'scorestd',
+             title  => 'Score STD',
+             align  => 'right',
+             color  => '#FFFFE6',
+             format => '%4.2f',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'Standard Deviation of Sequence Scores',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'scoremax',
+             title  => 'Score Max',
+             align  => 'right',
+             color  => '#FFFFE6',
+             format => '%4.2f',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'Maximum Sequence Score',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'scoremin',
+             title  => 'Score Min',
+             align  => 'right',
+             color  => '#FFFFE6',
+             format => '%4.2f',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'Minumum Sequence Score',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'scorecount',
+             title  => 'Score N',
+             align  => 'right',
+             color  => '#FFFFE6',
+             format => '%4d',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'Number of Students in score computations',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'countmean',
+             title  => 'Count Mean',
+             align  => 'right',
+             color  => '#FFFFFF',
+             format => '%4.2f',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'Mean Sequence Score',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'countstd',
+             title  => 'Count STD',
+             align  => 'right',
+             color  => '#FFFFFF',
+             format => '%4.2f',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'Standard Deviation of Sequence Scores',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'countmax',
+             title  => 'Count Max',
+             align  => 'right',
+             color  => '#FFFFFF',
+             format => '%4.2f',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'Maximum Number of Correct Problems',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'countmin',
+             title  => 'Count Min',
+             align  => 'right',
+             color  => '#FFFFFF',
+             format => '%4.2f',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'Minumum Number of Correct Problems',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'count',
+             title  => 'Count N',
+             align  => 'right',
+             color  => '#FFFFFF',
+             format => '%4d',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'Number of Students in score computations',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },
+           { name   => 'KR-21',
+             title  => 'KR-21',
+             align  => 'right',
+             color  => '#FFAAAA',
+             format => '%4.2f',
+             sortable  => 'no',
+             graphable => 'no',
+             long_title => 'KR-21 reliability statistic',
+             selectable => 'yes',
+             defaultselected => 'no',
+           },           
+);
+
+my %SelectedFields;
+
+sub parse_field_selection {
+    #
+    # Pull out the defaults
+    if (! defined($env{'form.fieldselections'})) {
+        $env{'form.fieldselections'} = [];
+        foreach my $field (@Fields) {
+            next if ($field->{'selectable'} ne 'yes');
+            if ($field->{'defaultselected'} eq 'yes') {
+                push(@{$env{'form.fieldselections'}},$field->{'name'});
+            }
+        }
+    }
+    #
+    # Make sure the data we are plotting is there
+    my %NeededFields;
+    if (exists($env{'form.plot'}) && $env{'form.plot'} ne '' &&
+        $env{'form.plot'} ne 'none') {
+        if ($env{'form.plot'} eq 'degrees') {
+            $NeededFields{'deg_of_diff'}++;
+            $NeededFields{'deg_of_disc'}++;
+        } elsif ($env{'form.plot'} eq 'tries statistics') {
+            $NeededFields{'mean_tries'}++;
+            $NeededFields{'std_tries'}++;
+            $NeededFields{'problem_num'}++;
+        } else {
+            $NeededFields{$env{'form.plot'}}++;
+        }
+    }
+    #
+    # This should not happen, but in case it does...
+    if (ref($env{'form.fieldselections'}) ne 'ARRAY') {
+        $env{'form.fieldselections'} = [$env{'form.fieldselections'}];
+    }
+    #
+    # Set the field data and the selected fields (for easier checking)
+    undef(%SelectedFields);
+    foreach my $field (@Fields) {
+        if ($field->{'selectable'} ne 'yes') {
+            $field->{'selected'} = 'yes';
+        } else {
+            $field->{'selected'} = 'no';
+        }
+        if (exists($NeededFields{$field->{'name'}})) {
+            $field->{'selected'} = 'yes';
+            $SelectedFields{$field->{'name'}}++;
+        }
+        foreach my $selection (@{$env{'form.fieldselections'}}) {
+            if ($selection eq $field->{'name'} || $selection eq 'all') {
+                $field->{'selected'} = 'yes';
+                $SelectedFields{$field->{'name'}}++;
+            }
+        }
+    }
+    #
+    # Always show all the sequence statistics (for now)
+    foreach my $field (@SeqFields) {
+        $field->{'selected'} = 'yes';
+    }
+    return;
+}
+
+sub field_selection_input {
+    my $Str = '<select name="fieldselections" multiple size="5">'."\n";
+    $Str .= '<option value="all">all</option>'."\n";
+    foreach my $field (@Fields) {
+        next if ($field->{'selectable'} ne 'yes');
+        $Str .= '    <option value="'.$field->{'name'}.'" ';
+        if ($field->{'selected'} eq 'yes') {
+            $Str .= 'selected ';
+        }
+        $Str .= '>'.$field->{'title'}.'</option>'."\n";
+    }
+    $Str .= "</select>\n";
+}
+
+###############################################
+###############################################
+
+=pod 
+
+=item &CreateInterface()
 
-#######################################################
-#######################################################
+Create the main intereface for the statistics page.  Allows the user to
+select sections, maps, and output.
+
+=cut
 
+###############################################
+###############################################
 sub CreateInterface {
+    my ($r) = @_;
+    #
+    &parse_field_selection();
+    #
     my $Str = '';
+    $Str .= &Apache::lonhtmlcommon::breadcrumbs('Overall Problem Statistics',
+						'Statistics_Overall_Key');
     $Str .= '<table cellspacing="5">'."\n";
     $Str .= '<tr>';
-    $Str .= '<td align="center"><b>Sections</b></td>';
-    $Str .= '<td align="center"><b>Sequences and Folders</b></td>';
-    $Str .= '<td align="center"><b>Output</b></td>';
+    $Str .= '<td align="center"><b>'.&mt('Sections').'</b></td>';
+    $Str .= '<td align="center"><b>'.&mt('Groups').'</b></td>';
+    $Str .= '<td align="center"><b>'.&mt('Access Status').'</b></td>';
+    $Str .= '<td align="center"><b>'.&mt('Sequences and Folders').'</b></td>';
+    $Str .= '<td align="center"><b>'.&mt('Statistics').'</b></td>';
+    $Str .= '<td rowspan="2">'.
+        &Apache::lonstathelpers::limit_by_time_form().'</td>';
     $Str .= '</tr>'."\n";
     #
     $Str .= '<tr><td align="center">'."\n";
     $Str .= &Apache::lonstatistics::SectionSelect('Section','multiple',5);
     $Str .= '</td><td align="center">';
+    $Str .= &Apache::lonstatistics::GroupSelect('Group','multiple',5);
+    $Str .= '</td><td align="center">';
+    $Str .= &Apache::lonhtmlcommon::StatusOptions(undef,undef,5);
+    $Str .= '</td><td align="center">';
     #
-    my $only_seq_with_assessments = sub { 
-        my $s=shift;
-        if ($s->{'num_assess'} < 1) { 
-            return 0;
-        } else { 
-            return 1;
-        }
-    };
-    $Str .= &Apache::lonstatistics::MapSelect('Maps','multiple,all',5,
-                                              $only_seq_with_assessments);
-    $Str .= '</td><td>'."\n";
-    $Str .= &CreateAndParseOutputSelector();
+    $Str .= &Apache::lonstatistics::map_select('Maps','multiple,all',5);
+    $Str .= '</td><td>'.&field_selection_input();
     $Str .= '</td></tr>'."\n";
     $Str .= '</table>'."\n";
+    #
+    $Str .= '<p><span class="LC_nobreak">'
+           .&mt('Status: [_1]',
+                    '<input type="text" name="stats_status"'
+                   .' size="60" value="" readonly="readonly" />')
+           .'</span></p>';
+    #
+    $Str .= '<input type="submit" name="GenerateStatistics" value="'.
+        &mt('Generate Statistics').'" />';
+    $Str .= '&nbsp;'x5;
+    $Str .= 'Plot '.&plot_dropdown().('&nbsp;'x10);
+    #
     return $Str;
 }
 
-#######################################################
-#######################################################
+###############################################
+###############################################
 
-=pod
+=pod 
 
-=item &CreateAndParseOutputSelector()
+=item &BuildProblemStatisticsPage()
+
+Main interface to problem statistics.
 
 =cut
 
-#######################################################
-#######################################################
-my $output_mode;
-my $show;
-
-my @OutputOptions = 
-    (
-     { name  => 'problem statistics grouped by sequence',
-       value => 'HTML problem statistics grouped',
-       description => 'Output statistics for the problem parts.',
-       mode => 'html',
-       show => 'grouped',
-     },
-     { name  => 'problem statistics ungrouped',
-       value => 'HTML problem statistics ungrouped',
-       description => 'Output statistics for the problem parts.',
-       mode => 'html',
-       show => 'ungrouped',
-     },
-     { name  => 'problem statistics, Excel',
-       value => 'Excel problem statistics',
-       description => 'Output statistics for the problem parts '.
-           'in an Excel workbook',
-       mode => 'excel',
-       show => 'all',
-     },
-     { name  => 'Degree of Difficulty Plot',
-       value => 'plot deg diff',
-       description => 'Generate a plot of the degree of difficulty of each '.
-           'problem part.',
-       mode => 'plot',
-       show => 'deg of diff',
-     },
-     { name  => 'Percent Wrong Plot',
-       value => 'plot per wrong',
-       description => 'Generate a plot showing the percent of students who '.
-           'were unable to complete each problem part',
-       mode => 'plot',
-       show => 'per wrong',
-     },
-     );
+###############################################
+###############################################
+my $navmap;
+my @sequences;
 
-sub OutputDescriptions {
-    my $Str = '';
-    $Str .= "<h2>Output Modes</h2>\n";
-    $Str .= "<dl>\n";
-    foreach my $outputmode (@OutputOptions) {
-	$Str .="    <dt>".$outputmode->{'name'}."</dt>\n";
-	$Str .="        <dd>".$outputmode->{'description'}."</dd>\n";
-    }
-    $Str .= "</dl>\n";
-    return $Str;
+sub clean_up {
+    undef($navmap);
+    undef(@sequences);
 }
 
-sub CreateAndParseOutputSelector {
-    my $Str = '';
-    my $elementname = 'outputmode';
+sub BuildProblemStatisticsPage {
+    my ($r,$c)=@_;
+    undef($navmap);
+    undef(@sequences);
     #
-    # Format for output options is 'mode, restrictions';
-    my $selected = 'html, with links';
-    if (exists($ENV{'form.'.$elementname})) {
-        if (ref($ENV{'form.'.$elementname} eq 'ARRAY')) {
-            $selected = $ENV{'form.'.$elementname}->[0];
-        } else {
-            $selected = $ENV{'form.'.$elementname};
-        }
-    }
+    my %Saveable_Parameters = ('Status' => 'scalar',
+                               'statsoutputmode' => 'scalar',
+                               'Section' => 'array',
+                               'Groups' => 'array',
+                               'StudentData' => 'array',
+                               'Maps' => 'array',
+                               'fieldselections'=> 'array');
+    &Apache::loncommon::store_course_settings('statistics',
+                                              \%Saveable_Parameters);
+    &Apache::loncommon::restore_course_settings('statistics',
+                                                \%Saveable_Parameters);
+    #
+    &Apache::lonstatistics::PrepareClasslist();
+    #
+    # Clear the package variables
+    undef(@StatsArray);
+    undef(%SeqStat);
+    #
+    # Finally let the user know we are here
+    my $interface = &CreateInterface($r);
+    $r->print($interface);
+    $r->print('<input type="hidden" name="sortby" value="'.$env{'form.sortby'}.
+              '" />');
     #
-    # Set package variables describing output mode
-    $output_mode = 'html';
-    $show        = 'all';
-    foreach my $option (@OutputOptions) {
-        next if ($option->{'value'} ne $selected);
-        $output_mode = $option->{'mode'};
-        $show        = $option->{'show'};
+    my @CacheButtonHTML = 
+        &Apache::lonstathelpers::manage_caches($r,'Statistics','stats_status');
+    my $Str;
+    foreach my $html (@CacheButtonHTML) {
+        $Str.=$html.('&nbsp;'x5);
+    }
+    #
+    $r->print($Str);
+    if (! exists($env{'form.firstrun'})) {
+        $r->print('<h3>'.
+                  &mt('Press "Generate Statistics" when you are ready.').
+                  '</h3><p>'.
+                  &mt('It may take some time to update the student data '.
+                      'for the first analysis.  Future analysis this session '.
+                      'will not have this delay.').
+                  '</p>');
+	&clean_up();
+        return;
     }
+    $r->rflush();
     #
-    # Build the form element
-    $Str = qq/<select size="5" name="$elementname">/;
-    foreach my $option (@OutputOptions) {
-        $Str .= "\n".'    <option value="'.$option->{'value'}.'"';
-        $Str .= " selected " if ($option->{'value'} eq $selected);
-        $Str .= ">".$option->{'name'}."<\/option>";
+    # This probably does not need to be done each time we are called, but
+    # it does not slow things down noticably.
+    &Apache::loncoursedata::populate_weight_table();
+    #
+    ($navmap,@sequences) = 
+        &Apache::lonstatistics::selected_sequences_with_assessments();
+    if (! ref($navmap)) {
+        $r->print('<h1>'.&mt('A course-wide error occurred.').'</h1>'.
+                  '<h3>'.$navmap.'</h3>');
+	&clean_up();
+        return;
     }
-    $Str .= "\n</select>";
-    return $Str;
+    if (exists($env{'form.Excel'})) {
+        $r->print('<h4>'.
+                  &Apache::lonstatistics::section_and_enrollment_description().
+                  '</h4>');
+        &Excel_output($r);
+    } else { 
+        $r->print('<input type="submit" name="Excel" value="'.
+                  &mt('Produce Excel Output').'" />'.'&nbsp;'x5);
+        $r->rflush();
+        $r->print('<h4>'.
+                  &Apache::lonstatistics::section_and_enrollment_description().
+                  '</h4>');
+        my $count = 0;
+        foreach my $seq (@sequences) {
+            my @resources = 
+                &Apache::lonstathelpers::get_resources($navmap,$seq);
+            $count += scalar(@resources);
+        }
+        if ($count > 10) {
+            $r->print('<h2>'.
+                      &mt('Compiling statistics for [_1] problems',$count).
+                      '</h2>');
+            if ($count > 30) {
+                $r->print('<h3>'.&mt('This will take some time.').'</h3>');
+            }
+            $r->rflush();
+        }
+        #
+        my $sortby = $env{'form.sortby'};
+        $sortby = 'container' if (! defined($sortby) || $sortby =~ /^\s*$/);
+        my $plot = $env{'form.plot'};
+        if ($plot eq '' || $plot eq 'none') {
+            undef($plot);
+        }
+        if ($sortby eq 'container' && ! defined($plot)) {
+            &output_sequence_statistics($r);
+            &output_html_by_sequence($r);
+        } else {
+            if (defined($plot)) {
+                &make_plot($r,$plot);
+            }
+            &output_html_stats($r);
+            &output_sequence_statistics($r);
+        }
+    }
+    &clean_up();
+    return;
 }
 
-###############################################
-###############################################
+sub output_sequence_statistics {
+    my ($r) = @_;
+    my $c=$r->connection();
+    $r->print('<h2>'.&mt('Sequence Statistics').
+	      &Apache::loncommon::help_open_topic('Statistics_Sequence').
+	      '</h2>');
+    $r->print('<table border="0"><tr><td bgcolor="#777777">'."\n".
+              '<table border="0" cellpadding="3">'."\n".
+              '<tr bgcolor="#FFFFE6">');
+    $r->print(&sequence_html_header());
+    foreach my $seq (@sequences) { 
+        last if ($c->aborted);
+        &compute_sequence_statistics($seq);
+        $r->print(&sequence_html_output($seq));
+    }
+    $r->print('</table>');
+    $r->print('</table>');
+    $r->rflush();
+    return;
+}
 
-###############################################
-###############################################
-sub Gather_Student_Data {
+
+##########################################################
+##########################################################
+##
+## HTML output routines
+##
+##########################################################
+##########################################################
+sub output_html_by_sequence {
     my ($r) = @_;
     my $c = $r->connection();
+    $r->print(&html_preamble());
     #
-    my @Sequences = &Apache::lonstatistics::Sequences_with_Assess();
-    #
-    my @Students = @Apache::lonstatistics::Students;
-    #
-    # Open the progress window
-    my %prog_state=&Apache::lonhtmlcommon::Create_PrgWin
-        ($r,'Statistics Compilation Status',
-         'Statistics Compilation Progress', scalar(@Students));
-    #
-    while (my $student = shift @Students) {
-        return if ($c->aborted());
-        my ($status,undef) = &Apache::loncoursedata::ensure_current_data
-            ($student->{'username'},$student->{'domain'},
-             $ENV{'request.course.id'});
-        &Apache::lonhtmlcommon::Increment_PrgWin($r,\%prog_state,
-                                                 'last student');
+    foreach my $seq (@sequences) {
+        last if ($c->aborted);
+        $r->print("<h3>".$seq->compTitle."</h3>".
+                  '<table border="0"><tr><td bgcolor="#777777">'."\n".
+                  '<table border="0" cellpadding="3">'."\n".
+                  '<tr bgcolor="#FFFFE6">'.
+                  &statistics_table_header('no container')."</tr>\n");
+        my @Data = &compute_statistics_on_sequence($seq);
+        foreach my $data (@Data) {
+            $r->print('<tr>'.&statistics_html_table_data($data,
+                                                         'no container').
+                      "</tr>\n");
+        }
+        $r->print('</table>'."\n".'</table>'."\n");
+        $r->rflush();
     }
-    &Apache::lonhtmlcommon::Close_PrgWin($r,\%prog_state);
-    $r->rflush();
+    return;
 }
 
+sub output_html_stats {
+    my ($r)=@_;
+    &compute_all_statistics($r);
+    $r->print(&html_preamble());
+    &sort_data($env{'form.sortby'});
+    #
+    my $count=0;
+    foreach my $data (@StatsArray) {
+        if ($count++ % 50 == 0) {
+            $r->print("</table>\n</table>\n");
+            $r->print('<table border="0"><tr><td bgcolor="#777777">'."\n".
+                      '<table border="0" cellpadding="3">'."\n".
+                      '<tr bgcolor="#FFFFE6">'.
+                      '<tr bgcolor="#FFFFE6">'.
+                      &statistics_table_header().
+                      "</tr>\n");
+        }
+        $r->print('<tr>'.&statistics_html_table_data($data)."</tr>\n");
+    }
+    $r->print("</table>\n</table>\n");
+    return;
+}
+
+sub html_preamble {
+    my $Str='';
+    $Str .= "<h2>".
+        $env{'course.'.$env{'request.course.id'}.'.description'}.
+        "</h2>\n";
+    my ($starttime,$endtime) = &Apache::lonstathelpers::get_time_limits();
+    if (defined($starttime) || defined($endtime)) {
+        # Inform the user what the time limits on the data are.
+        $Str .= '<h3>'.&mt('Statistics on submissions from [_1] to [_2]',
+                           &Apache::lonlocal::locallocaltime($starttime),
+                           &Apache::lonlocal::locallocaltime($endtime)
+                           ).'</h3>';
+    }
+    $Str .= "<h3>".&mt('Compiled on [_1]',
+                       &Apache::lonlocal::locallocaltime(time))."</h3>";
+    return $Str;
+}
+
+
 ###############################################
 ###############################################
-
+##
+## Misc HTML output routines
+##
 ###############################################
 ###############################################
-sub BuildProblemStatisticsPage {
-    my ($r,$c)=@_;
-    #
-    $output_mode = 'html';
-    $show = 'grouped';
+sub statistics_html_table_data {
+    my ($data,$options) = @_;
+    my $row = '';
+    foreach my $field (@Fields) {
+        next if ($options =~ /no $field->{'name'}/);
+        next if ($field->{'selected'} ne 'yes');
+        $row .= '<td bgcolor="'.$field->{'color'}.'"';
+        if (exists($field->{'align'})) {
+            $row .= ' align="'.$field->{'align'}.'"';
+            }
+        $row .= '>';
+        if (exists($field->{'special'}) && $field->{'special'} eq 'link') {
+            $row .= '<a href="'.$data->{$field->{'name'}.'.link'}.'">';
+        }
+        if (exists($field->{'format'}) && $data->{$field->{'name'}} !~ /[A-Z]/i) {
+            $row .= sprintf($field->{'format'},$data->{$field->{'name'}});
+        } else {
+            $row .= $data->{$field->{'name'}};
+        }
+        if (exists($field->{'special'}) && $field->{'special'} eq 'link') {
+            $row.= '</a>';
+        }
+        $row .= '</td>';
+    }
+    return $row;
+}
+
+sub statistics_table_header {
+    my ($options) = @_;
+    my $header_row;
+    foreach my $field (@Fields) {
+        next if ($options =~ /no $field->{'name'}/);
+        next if ($field->{'selected'} ne 'yes');
+        $header_row .= '<th>';
+        if (exists($field->{'sortable'}) && $field->{'sortable'} eq 'yes') {
+            $header_row .= '<a href="javascript:'.
+                'document.Statistics.sortby.value='."'".$field->{'name'}."'".
+                    ';document.Statistics.submit();">';
+        }
+        $header_row .= &mt($field->{'title'});
+        if ($options =~ /sortable/) {
+            $header_row.= '</a>';
+        }
+        if ($options !~ /no plots/        && 
+            exists($field->{'graphable'}) && 
+            $field->{'graphable'} eq 'yes') {
+            $header_row.=' (';
+            $header_row .= '<a href="javascript:'.
+                "document.Statistics.plot.value='$field->{'name'}'".
+                    ';document.Statistics.submit();">';
+            $header_row .= &mt('plot').'</a>)';
+        }
+        $header_row .= '</th>';
+    }
+    return $header_row;
+}
+
+sub sequence_html_header {
+    my $Str .= '<tr>';
+    foreach my $field (@SeqFields) {
+#        next if ($field->{'selected'} ne 'yes');
+        $Str .= '<th bgcolor="'.$field->{'color'}.'"';
+        $Str .= '>'.$field->{'title'}.'</th>';
+    }
+    $Str .= '</tr>';
+    return $Str;
+}
+
+
+sub sequence_html_output {
+    my ($seq) = @_;
+    my $data = $SeqStat{$seq->symb};
+    my $row = '<tr>';
+    foreach my $field (@SeqFields) {
+        next if ($field->{'selected'} ne 'yes');
+        $row .= '<td bgcolor="'.$field->{'color'}.'"';
+        if (exists($field->{'align'})) {
+            $row .= ' align="'.$field->{'align'}.'"';
+        }
+        $row .= '>';
+        if (exists($field->{'format'})) {
+            $row .= sprintf($field->{'format'},$data->{$field->{'name'}});
+        } else {
+            $row .= $data->{$field->{'name'}};
+        }
+        $row .= '</td>';
+    }
+    $row .= '</tr>'."\n";
+    return $row;
+}
+
+####################################################
+####################################################
+##
+##    Plotting Routines
+##
+####################################################
+####################################################
+sub make_plot {
+    my ($r,$plot) = @_;
+    &compute_all_statistics($r);
+    &sort_data($env{'form.sortby'});
+    if ($plot eq 'degrees') {
+        &degrees_plot($r);
+    } elsif ($plot eq 'tries statistics') {
+        &tries_data_plot($r);
+    } else {
+        &make_single_stat_plot($r,$plot);
+    }
+    return;
+}
+
+sub make_single_stat_plot {
+    my ($r,$datafield) = @_;
     #
-    $r->print(&CreateInterface());
-    $r->print('<input type="hidden" name="statsfirstcall" value="no" />');
-    $r->print('<input type="hidden" name="sortby" value="'.$ENV{'form.sortby'}.
-              '" />');
-    if (! exists($ENV{'form.statsfirstcall'})) {
+    my $title; my $yaxis;
+    foreach my $field (@Fields) {
+        next if ($field->{'name'} ne $datafield);
+        $title = $field->{'long_title'};
+        $yaxis = $field->{'title'};
+        last;
+    }
+    if ($title eq '' || $yaxis eq '') {
+        # datafield is something we do not know enough about to plot
+        $r->print('<h3>'.
+                  &mt('Unable to plot the requested statistic.').
+                  '</h3>');
         return;
     }
     #
-    &Gather_Student_Data($r);
+    # Build up the data sets to plot
+    my @Labels; 
+    my @Data;
+    my $max = 1;
+    foreach my $data (@StatsArray) {
+        push(@Labels,$data->{'problem_num'});
+        push(@Data,$data->{$datafield});
+        if ($data->{$datafield}>$max) {
+            $max = $data->{$datafield};
+        }
+    }
+    foreach (1,2,3,4,5,10,15,20,25,40,50,75,100,150,200,250,300,500,600,750,
+             1000,1500,2000,2500,3000,3500,4000,5000,7500,10000,15000,20000) {
+        if ($max <= $_) {
+            $max = $_;
+            last;
+        }
+    }
+    if ($max > 20000) {
+        $max = 10000*(int($max/10000)+1);
+    }
     #
+    $r->print("<p>".&Apache::loncommon::DrawBarGraph($title,
+                                                     'Problem Number',
+                                                     $yaxis,
+                                                     $max,
+                                                     undef, # colors
+                                                     \@Labels,
+                                                     \@Data)."</p>\n");
+    return;
+}
+
+sub degrees_plot {
+    my ($r)=@_;
+    my $count = scalar(@StatsArray);
+    my $width = 50 + 10*$count;
+    $width = 300 if ($width < 300);
+    my $height = 300;
+    my $plot = '';
+    my $ymax = 0;
+    my $ymin = 0;
+    my @Disc; my @Diff; my @Labels;    
+    foreach my $data (@StatsArray) {
+        push(@Labels,$data->{'problem_num'});
+        my $disc = $data->{'deg_of_disc'};
+        my $diff = $data->{'deg_of_diff'};
+        push(@Disc,$disc);
+        push(@Diff,$diff);
+        #
+        $ymin = $disc if ($ymin > $disc);
+        $ymin = $diff if ($ymin > $diff);
+        $ymax = $disc if ($ymax < $disc);
+        $ymax = $diff if ($ymax < $diff);
+    }
+    #
+    # Make sure we show relevant information.
+    if ($ymin < 0) {
+        if (abs($ymin) < 0.05) {
+            $ymin = 0;
+        } else {
+            $ymin = -1;
+        }
+    }
+    if ($ymax > 0) {
+        if (abs($ymax) < 0.05) {
+            $ymax = 0;
+        } else {
+            $ymax = 1;
+        }
+    }
     #
-    if ($output_mode eq 'html') {
-        $r->print("<h2>".
-                  $ENV{'course.'.$ENV{'request.course.id'}.'.description'}.
-                  "</h2>\n");
-        $r->print("<h3>".localtime(time)."</h3>");
-        $r->rflush();
-        if ($show eq 'grouped') {
-            &output_html_grouped_by_sequence($r);
-        } elsif ($show eq 'ungrouped') {
-            &output_html_ungrouped($r);
+    my $xmax = $Labels[-1];
+    if ($xmax > 50) {
+        if ($xmax % 10 != 0) {
+            $xmax = 10 * (int($xmax/10)+1);
         }
     } else {
-        $r->print("<h1>Not implemented</h1>");
+        if ($xmax % 5 != 0) {
+            $xmax = 5 * (int($xmax/5)+1);
+        }
     }
+    #
+    my $discdata .= '<data>'.join(',',@Labels).'</data>'.$/.
+                    '<data>'.join(',',@Disc).'</data>'.$/;
+    #
+    my $diffdata .= '<data>'.join(',',@Labels).'</data>'.$/.
+                    '<data>'.join(',',@Diff).'</data>'.$/;
+    #
+    my $title = 'Degree of Discrimination\nand Degree of Difficulty';
+    if ($xmax > 50) {
+        $title = 'Degree of Discrimination and Degree of Difficulty';
+    }
+    #
+    $plot=<<"END";
+<gnuplot 
+    texfont="10"
+    fgcolor="x000000"
+    plottype="Cartesian"
+    font="large"
+    grid="on"
+    align="center"
+    border="on"
+    transparent="on"
+    alttag="Degree of Discrimination and Degree of Difficulty Plot"
+    samples="100"
+    bgcolor="xffffff"
+    height="$height"
+    width="$width">
+    <key 
+        pos="top right"
+        title=""
+        box="off" />
+    <title>$title</title>
+    <axis xmin="0" ymin="$ymin" xmax="$xmax" ymax="$ymax" color="x000000" />
+    <xlabel>Problem Number</xlabel>
+    <curve 
+        linestyle="linespoints" 
+        name="DoDisc" 
+        pointtype="0" 
+        color="x000000">
+        $discdata
+    </curve>
+    <curve 
+        linestyle="linespoints" 
+        name="DoDiff" 
+        pointtype="0" 
+        color="xFF0000">
+        $diffdata
+    </curve>
+</gnuplot>
+END
+    my $plotresult = 
+        '<p>'.&Apache::lonxml::xmlparse($r,'web',$plot).'</p>'.$/;
+    $r->print($plotresult);
     return;
 }
 
-sub output_html_grouped_by_sequence {
-    my ($r) = @_;
-    #$r->print(&ProblemStatisticsLegend());
-    my @Header = ("Title","Part","#Stdnts","Tries","Mod",
-                  "Mean","#YES","#yes","%Wrng","DoDiff",
-                  "S.D.","Skew.");#,"D.F.1st","D.F.2nd");
-    # #FFFFE6 #EEFFCC #DDFFFF FFDDDD #DDFFDD #FFDDFF
-    foreach my $sequence (&Apache::lonstatistics::Sequences_with_Assess()) {
-        my $show_part = 0;
-        next if ($sequence->{'num_assess'}<1);
-        $r->print("<h3>".$sequence->{'title'}."</h3>");
-        $r->print('<table border="0"><tr><td bgcolor="#777777">'."\n");
-        $r->print('<table border="0" cellpadding="3">'."\n");
-        $r->print('<tr bgcolor="#FFFFE6"><th>'.
-                  join("</th><th>",@Header)."</th></tr>\n");
-        foreach my $resource (@{$sequence->{'contents'}}) {
-            next if ($resource->{'type'} ne 'assessment');
-            foreach my $part (@{$resource->{'parts'}}) {
-                my ($num,$tries,$mod,$mean,$Solved,$solved,$DegOfDiff,$STD,
-                    $SKEW) = &Apache::loncoursedata::get_problem_statistics
-                        (undef,$resource->{'symb'},$part,
-                         $ENV{'request.course.id'});
-                #
-                $show_part = 1 if ($part ne '0');
-                $part = '&nbsp;' if ($part == 0);
-                #
-                my $wrongpercent = 0;
-                if (defined($num) && $num > 0) {
-                    $wrongpercent=int(10*100*($num-$Solved+$solved)/$num)/10;
-                }
-                $r->print('<tr>'.&statistics_html_table_data
-                          ($resource,$part,$num,$tries,$mod,$mean,$Solved,
-                           $solved,$wrongpercent,$DegOfDiff,$STD,$SKEW,
-                           $show_part).
-                          "</tr>\n");
-            }
+sub tries_data_plot {
+    my ($r)=@_;
+    my $count = scalar(@StatsArray);
+    my $width = 50 + 10*$count;
+    $width = 300 if ($width < 300);
+    my $height = 300;
+    my $plot = '';
+    my @STD;  my @Mean; my @Max; my @Min;
+    my @Labels;
+    my $ymax = 5;
+    foreach my $data (@StatsArray) {
+        my $max = $data->{'mean_tries'} + $data->{'std_tries'};
+        $ymax = $max if ($ymax < $max);
+        $ymax = $max if ($ymax < $max);
+        push(@Labels,$data->{'problem_num'});
+        push(@STD,$data->{'std_tries'});
+        push(@Mean,$data->{'mean_tries'});
+    }
+    #
+    # Make sure we show relevant information.
+    my $xmax = $Labels[-1];
+    if ($xmax > 50) {
+        if ($xmax % 10 != 0) {
+            $xmax = 10 * (int($xmax/10)+1);
+        }
+    } else {
+        if ($xmax % 5 != 0) {
+            $xmax = 5 * (int($xmax/5)+1);
         }
-        $r->print("</table>\n");
-        $r->print("</td></tr></table>\n");
-        $r->rflush();
     }
+    $ymax = int($ymax)+1+2;
+    #
+    my $std_data .= '<data>'.join(',',@Labels).'</data>'.$/.
+                    '<data>'.join(',',@Mean).'</data>'.$/;
     #
+    my $std_error_data .= '<data>'.join(',',@Labels).'</data>'.$/.
+                          '<data>'.join(',',@Mean).'</data>'.$/.
+                          '<data>'.join(',',@STD).'</data>'.$/;
+    #
+    my $title = 'Mean and S.D. of Tries';
+    if ($xmax > 25) {
+        $title = 'Mean and Standard Deviation of Tries';
+    }
+    #
+    $plot=<<"END";
+<gnuplot 
+    texfont="10"
+    fgcolor="x000000"
+    plottype="Cartesian"
+    font="large"
+    grid="on"
+    align="center"
+    border="on"
+    transparent="on"
+    alttag="Mean and S.D of Tries Plot"
+    samples="100"
+    bgcolor="xffffff"
+    height="$height"
+    width="$width">
+    <title>$title</title>
+    <axis xmin="0" ymin="0" xmax="$xmax" ymax="$ymax" color="x000000" />
+    <xlabel>Problem Number</xlabel>
+    <ylabel>Number of Tries</ylabel>
+    <curve 
+        linestyle="yerrorbars"
+        name="S.D. Tries" 
+        pointtype="1" 
+        color="x666666">
+        $std_error_data
+    </curve>
+    <curve 
+        linestyle="points"
+        name="Mean Tries" 
+        pointtype="1" 
+        color="xCC4444">
+        $std_data
+    </curve>
+</gnuplot>
+END
+    my $plotresult = 
+        '<p>'.&Apache::lonxml::xmlparse($r,'web',$plot).'</p>'.$/;
+    $r->print($plotresult);
     return;
 }
 
+sub plot_dropdown {
+    my $current = '';
+    #
+    if (defined($env{'form.plot'})) {
+        $current = $env{'form.plot'};
+    }
+    #
+    my @Additional_Plots = (
+                            { graphable=>'yes',
+                              name => 'degrees',
+                              title => 'Difficulty Indexes' },
+                            { graphable=>'yes',
+                              name => 'tries statistics',
+                              title => 'Tries Statistics' });
+    #
+    my $Str= "\n".'<select name="plot" size="1">';
+    $Str .= '<option name="none"></option>'."\n";
+    $Str .= '<option name="none2">none</option>'."\n";
+    foreach my $field (@Additional_Plots,@Fields) {
+        if (! exists($field->{'graphable'}) ||
+            $field->{'graphable'} ne 'yes') {
+            next;
+        }
+        $Str .= '<option value="'.$field->{'name'}.'"';
+        if ($field->{'name'} eq $current) {
+            $Str .= ' selected ';
+        }
+        $Str.= '>'.&mt($field->{'title'}).'</option>'."\n";
+    }
+    $Str .= '</select>'."\n";
+    return $Str;
+}
 
 ###############################################
 ###############################################
-
+##
+## Excel output routines
+##
 ###############################################
 ###############################################
-sub output_html_ungrouped {
+sub Excel_output {
     my ($r) = @_;
-    #
-    my $show_container = 0;
-    my $show_part = 0;
-    #$r->print(&ProblemStatisticsLegend());
-    my @Header = ("Title","Part","#Stdnts","Tries","Mod",
-                  "Mean","#YES","#yes","%Wrng","DoDiff",
-                  "S.D.","Skew");#,"D.F.1st","D.F.2nd");
-    #
-    my $sortby = undef;
-    foreach (@Header) {
-        if ($ENV{'form.sortby'} eq $_) {
-            $sortby = $_;
+    $r->print('<h2>'.&mt('Preparing Excel Spreadsheet').'</h2>');
+    ##
+    ## Compute the statistics
+    &compute_all_statistics($r);
+    my $c = $r->connection;
+    return if ($c->aborted());
+    #
+    my ($starttime,$endtime) = &Apache::lonstathelpers::get_time_limits();
+    ##
+    ## Create the excel workbook
+    my ($excel_workbook,$filename,$format) =
+        &Apache::loncommon::create_workbook($r);
+    return if (! defined($excel_workbook));
+    #
+    # Add a worksheet
+    my $sheetname = $env{'course.'.$env{'request.course.id'}.'.description'};
+    if (length($sheetname) > 31) {
+        $sheetname = substr($sheetname,0,31);
+    }
+    my $excel_sheet = $excel_workbook->addworksheet(
+        &Apache::loncommon::clean_excel_name($sheetname));
+    ##
+    ## Begin creating excel sheet
+    ##
+    my ($rows_output,$cols_output) = (0,0);
+    #
+    # Put the course description in the header
+    $excel_sheet->write($rows_output,$cols_output++,
+                   $env{'course.'.$env{'request.course.id'}.'.description'},
+                        $format->{'h1'});
+    $cols_output += 3;
+    #
+    # Put a description of the sections listed
+    my $sectionstring = '';
+    $excel_sheet->write($rows_output,$cols_output++,
+                        &Apache::lonstatistics::section_and_enrollment_description('plaintext'),
+                        $format->{'h3'});
+    $cols_output += scalar(&Apache::lonstatistics::get_selected_sections());
+    $cols_output += scalar(&Apache::lonstatistics::get_selected_groups());
+    #
+    # Time restrictions
+    my $time_string;
+    if (defined($starttime)) {
+        # call localtime but not lonlocal:locallocaltime because excel probably
+        # cannot handle localized text.  Probably.
+        $time_string .= 'Data collected from '.localtime($time_string);
+        if (defined($endtime)) {
+            $time_string .= ' to '.localtime($endtime);
         }
+        $time_string .= '.';
+    } elsif (defined($endtime)) {
+        # See note above about lonlocal:locallocaltime
+        $time_string .= 'Data collected before '.localtime($endtime).'.';
+    }
+    if (defined($time_string)) {
+        $excel_sheet->write($rows_output,$cols_output++,$time_string);
+        $cols_output+= 5;
+    }
+    #
+    # Put the date in there too
+    $excel_sheet->write($rows_output,$cols_output++,
+                        'Compiled on '.localtime(time));
+    #
+    $rows_output++; 
+    $cols_output=0;
+    ##
+    ## Sequence Statistics
+    ## 
+    &write_headers($excel_sheet,$format,\$rows_output,\$cols_output,
+                   \@SeqFields);
+    foreach my $seq (@sequences) {
+        my $data = $SeqStat{$seq->symb};
+        $cols_output=0;
+        foreach my $field (@SeqFields) {
+            next if ($field->{'selected'} ne 'yes');
+            my $fieldformat = undef;
+            if (exists($field->{'excel_format'})) {
+                $fieldformat = $format->{$field->{'excel_format'}};
+            }
+            $excel_sheet->write($rows_output,$cols_output++,
+                                $data->{$field->{'name'}},$fieldformat);
+        }
+        $rows_output++;
+        $cols_output=0;
     }
-    if (! defined($sortby) || $sortby eq '') {
-        $sortby = 'Container';
-    }
-    # #FFFFE6 #EEFFCC #DDFFFF FFDDDD #DDFFDD #FFDDFF
-    my @Sequences = &Apache::lonstatistics::Sequences_with_Assess();
-    if (@Sequences > 1) {
-        unshift(@Header,"Container");
-        $show_container = 1;
-    }
-    #
-    $r->print('<table border="0"><tr><td bgcolor="#777777">'."\n");
-    $r->rflush();
-    #
-    # Compile the data
-    my @Statsarray;
-    foreach my $sequence (@Sequences) {
-        next if ($sequence->{'num_assess'}<1);
-        foreach my $resource (@{$sequence->{'contents'}}) {
-            next if ($resource->{'type'} ne 'assessment');
-            foreach my $part (@{$resource->{'parts'}}) {
-                my ($num,$tries,$mod,$mean,$Solved,$solved,$DegOfDiff,$STD,
-                    $SKEW) = &Apache::loncoursedata::get_problem_statistics
-                        (undef,$resource->{'symb'},$part,
-                         $ENV{'request.course.id'});
-                #
-                $show_part = 1 if ($part ne '0');
-                $part = '&nbsp;' if ($part == 0);
-                #
-                my $wrongpercent = 0;
-                if (defined($num) && $num > 0) {
-                    $wrongpercent=int(10*100*($num-$Solved+$solved)/$num)/10;
-                }
-                push (@Statsarray,
-                      { 'sequence' => $sequence,
-                        'resource' => $resource,
-                        'Title' => $resource->{'title'},
-                        'Part'  => $part,
-                        '#Stdnts' => $num,
-                        'Tries' => $tries,
-                        'Mod' => $mod,
-                        'Mean' => $mean,
-                        '#YES' => $Solved,
-                        '#yes' => $solved,
-                        '%Wrng' => $wrongpercent,
-                        'DoDiff' => $DegOfDiff,
-                        'S.D.' => $STD,
-                        'Skew' => $SKEW,
-                      });
+    ##
+    ## Resource Statistics
+    ##
+    $rows_output++;
+    $cols_output=0;
+    &write_headers($excel_sheet,$format,\$rows_output,\$cols_output,
+                   \@Fields);
+    #
+    foreach my $data (@StatsArray) {
+        $cols_output=0;
+        foreach my $field (@Fields) {
+            next if ($field->{'selected'} ne 'yes');
+            next if ($field->{'name'} eq 'problem_num');
+            my $fieldformat = undef;
+            if (exists($field->{'excel_format'})) {
+                $fieldformat = $format->{$field->{'excel_format'}};
             }
+            $excel_sheet->write($rows_output,$cols_output++,
+                                $data->{$field->{'name'}},$fieldformat);
         }
+        $rows_output++;
+        $cols_output=0;
     }
     #
-    # Table Headers
-    $r->print('<table border="0" cellpadding="3">'."\n");
-    my $Str = '';
-    foreach (@Header) {
-        next if ($_ eq 'Part' && !$show_part);
-        # Do not allow sorting on some fields
-        if ($_ eq $sortby || /^(Part)$/) {  
-            $Str .= '<th>'.$_.'</th>';
+    $excel_workbook->close();
+    #
+    # Tell the user where to get their excel file
+    $r->print('<br />'.
+              '<a href="'.$filename.'">'.
+              &mt('Your Excel Spreadsheet').'</a>'."\n");
+    $r->rflush();
+    return;
+}
+
+##
+## &write_headers
+##
+sub write_headers {
+    my ($excel_sheet,$format,$rows_output,$cols_output,$Fields) = @_;
+    ##
+    ## First the long titles
+    foreach my $field (@{$Fields}) {
+        next if ($field->{'name'} eq 'problem_num');
+        next if ($field->{'selected'} ne 'yes');
+        if (exists($field->{'long_title'})) {
+            $excel_sheet->write($$rows_output,${$cols_output},
+                                $field->{'long_title'},
+                                $format->{'bold'});
         } else {
-            $Str .= '<th>'.
-     '<a href="javascript:document.Statistics.sortby.value='."'$_'".
-         ';document.Statistics.submit();">'.
-             $_.'</a></th>';
+            $excel_sheet->write($$rows_output,${$cols_output},'');
+        }
+        ${$cols_output}+= 1;
+    }
+    ${$cols_output} =0;
+    ${$rows_output}+=1;
+    ##
+    ## Then the short titles
+    foreach my $field (@{$Fields}) {
+        next if ($field->{'selected'} ne 'yes');
+        next if ($field->{'name'} eq 'problem_num');
+        # Use english for excel as I am not sure how well excel handles 
+        # other character sets....
+        $excel_sheet->write($$rows_output,$$cols_output,
+                            $field->{'title'},
+                            $format->{'bold'});
+        $$cols_output+=1;
+    }
+    ${$cols_output} =0;
+    ${$rows_output}+=1;
+    return;
+}
+
+##################################################
+##################################################
+##
+## Statistics Gathering and Manipulation Routines
+##
+##################################################
+##################################################
+sub compute_statistics_on_sequence {
+    my ($seq) = @_;
+    my @Data;
+    foreach my $res (&Apache::lonstathelpers::get_resources($navmap,$seq)) {
+        foreach my $part (@{$res->parts}) {
+            next if ($res->is_survey($part));
+            #
+            # This is where all the work happens
+            my $data = &get_statistics($seq,$res,$part,scalar(@StatsArray)+1);
+            push (@Data,$data);
+            push (@StatsArray,$data);
         }
     }
-    $r->print('<tr bgcolor="#FFFFE6">'.$Str."</tr>\n");
+    return @Data;
+}
+
+sub compute_all_statistics {
+    my ($r) = @_;
+    if (@StatsArray > 0) {
+        # Assume we have already computed the statistics
+        return;
+    }
+    my $c = $r->connection;
+    foreach my $seq (@sequences) {
+        last if ($c->aborted);
+        &compute_sequence_statistics($seq);
+        &compute_statistics_on_sequence($seq);
+    }
+}
+
+sub sort_data {
+    my ($sortkey) = @_;
+    return if (! @StatsArray);
     #
     # Sort the data
-    my @OutputOrder;
-    if ($sortby eq 'Container') {
-        @OutputOrder = @Statsarray;
-    } else {
+    my $sortby = undef;
+    foreach my $field (@Fields) {
+        if ($sortkey eq $field->{'name'}) {
+            $sortby = $field->{'name'};
+        }
+    }
+    if (! defined($sortby) || $sortby eq '' || $sortby eq 'problem_num') {
+        $sortby = 'container';
+    }
+    if ($sortby ne 'container') {
         # $sortby is already defined, so we can charge ahead
         if ($sortby =~ /^(title|part)$/i) {
             # Alpha comparison
-            @OutputOrder = sort {
+            @StatsArray = sort {
                 lc($a->{$sortby}) cmp lc($b->{$sortby}) ||
-                    lc($a->{'Title'}) cmp lc($b->{'Title'}) ||
-                        lc($a->{'Part'}) cmp lc($b->{'Part'});
-            } @Statsarray;
+                lc($a->{'title'}) cmp lc($b->{'title'}) ||
+                lc($a->{'part'}) cmp lc($b->{'part'});
+            } @StatsArray;
         } else {
             # Numerical comparison
-            @OutputOrder = sort {
+            @StatsArray = sort {
                 my $retvalue = 0;
                 if ($b->{$sortby} eq 'nan') {
                     if ($a->{$sortby} ne 'nan') {
@@ -401,394 +1512,296 @@ sub output_html_ungrouped {
                     }
                 }
                 if ($retvalue eq '0') {
-                    $retvalue = $b->{$sortby} <=> $a->{$sortby} ||
-                                lc($a->{'Title'}) <=> lc($b->{'Title'}) ||
-                                lc($a->{'Part'})  <=> lc($b->{'Part'});
+                    $retvalue = $b->{$sortby} <=> $a->{$sortby}     ||
+                            lc($a->{'title'}) <=> lc($b->{'title'}) ||
+                            lc($a->{'part'})  <=> lc($b->{'part'});
                 }
                 $retvalue;
-            } @Statsarray;
-        }
-    }
-    foreach my $row (@OutputOrder) {
-        $r->print('<tr>');
-        if ($show_container) {
-            $r->print('<td bgcolor="#FFFFE6">'
-                      .$row->{'sequence'}->{'title'}.'</td>');
+            } @StatsArray;
         }
-        $r->print(&stats_row_from_hash($row,$show_part));
-        $r->print("</tr>\n");
     }
-    $r->print("</table>\n");
-    $r->print("</td></tr></table>\n");
-    $r->rflush();
     #
+    # Renumber the data set
+    my $count;
+    foreach my $data (@StatsArray) {
+        $data->{'problem_num'} = ++$count;
+    }
     return;
 }
 
-sub stats_row_from_hash {
-    my ($data,$show_part) = @_;
-    return &statistics_html_table_data($data->{'resource'},$data->{'Part'},
-                                       $data->{'#Stdnts'}, $data->{'Tries'},
-                                       $data->{'Mod'},     $data->{'Mean'},
-                                       $data->{'#YES'},    $data->{'#yes'},
-                                       $data->{"\%Wrng"},  $data->{'DoDiff'},
-                                       $data->{'S.D.'},    $data->{'Skew'},
-                                       $show_part);
+########################################################
+########################################################
+
+=pod
+
+=item &get_statistics()
+
+Wrapper routine from the call to loncoursedata::get_problem_statistics.  
+Calls lonstathelpers::get_time_limits() to limit the data set by time
+and &compute_discrimination_factor
+
+Inputs: $sequence, $resource, $part, $problem_num
+
+Returns: Hash reference with statistics data from 
+loncoursedata::get_problem_statistics.
+
+=cut
+
+########################################################
+########################################################
+sub get_statistics {
+    my ($sequence,$resource,$part,$problem_num) = @_;
+    #
+    my ($starttime,$endtime) = &Apache::lonstathelpers::get_time_limits();
+    my $symb = $resource->symb;
+    my $courseid = $env{'request.course.id'};
+    #
+    my $data = &Apache::loncoursedata::get_problem_statistics
+                        ([&Apache::lonstatistics::get_selected_sections()],
+                         [&Apache::lonstatistics::get_selected_groups()],
+                         $Apache::lonstatistics::enrollment_status,
+                         $symb,$part,$courseid,$starttime,$endtime);
+    $data->{'symb'}        = $symb;
+    $data->{'part'}        = $part;
+    $data->{'problem_num'} = $problem_num;
+    $data->{'container'}   = $sequence->compTitle;
+    $data->{'title'}       = $resource->compTitle;
+    $data->{'title.link'}  = $resource->src.'?symb='.
+        &escape($resource->symb);
+    #
+    if ($SelectedFields{'deg_of_disc'}) {
+        $data->{'deg_of_disc'} = 
+            &compute_discrimination_factor($resource,$part,$sequence);
+    }
+    #
+    # Store in metadata if computations were done for all students
+    if ($data->{'num_students'} > 1) {
+        my @Sections = &Apache::lonstatistics::get_selected_sections();
+        my $sections = '"'.join(' ',@Sections).'"';
+        $sections =~ s/&+/_/g;  # Ensure no special characters
+        $data->{'sections'}=$sections;
+        $data->{'course'} = $env{'request.course.id'};
+        my $urlres=(&Apache::lonnet::decode_symb($resource->symb))[2];
+        $data->{'urlres'}=$urlres;
+        my %storestats = 
+            &LONCAPA::lonmetadata::dynamic_metadata_storage($data);
+        my ($dom,$user) = ($urlres=~m{^($LONCAPA::domain_re)/($LONCAPA::username_re)}); 
+        &Apache::lonnet::put('nohist_resevaldata',\%storestats,$dom,$user);
+    }
+    #
+    $data->{'tries_per_correct'} = $data->{'tries'} / 
+        ($data->{'num_solved'}+0.1);
+    #
+    # Get the due date for research purposes (commented out most of the time)
+#    my $duedate = &Apache::lonnet::EXT('resource.'.$part.'.duedate',$symb);;
+#    my $opendate = &Apache::lonnet::EXT('resource.'.$part.'.opendate',$symb);
+#    my $maxtries = &Apache::lonnet::EXT('resource.'.$part.'.maxtries',$symb);
+#    my $hinttries = &Apache::lonnet::EXT('resource.'.$part.'.hinttries',$symb);
+    my $weight = &Apache::lonnet::EXT('resource.'.$part.'.weight',$symb);
+    $data->{'weight'} = $weight;
+#    $data->{'duedate'} = $duedate; 
+#    $data->{'opendate'} = $opendate;
+#    $data->{'maxtries'} = $maxtries;
+#    $data->{'hinttries'} = $hinttries;
+#    $data->{'resptypes'} = join(',',@{$resource->{'partdata'}->{$part}->{'ResponseTypes'}});
+    return $data;
 }
 
 ###############################################
 ###############################################
 
+=pod
+
+=item &compute_discrimination_factor()
+
+Inputs: $Resource, $Sequence
+
+Returns: integer between -1 and 1
+
+=cut
+
 ###############################################
 ###############################################
-sub statistics_html_table_data {
-    my ($resource,$part,$num,$tries,$mod,$mean,$Solved,$solved,$wrongpercent,
-        $DegOfDiff,$STD,$SKEW,$show_part) = @_;
-    my $row = '';
-    $row .= '<td bgcolor="#FFFFE6">'.
-        '<a href="'.$resource->{'src'}.'" target="_blank" >'.
-            $resource->{'title'}.'</a>'.
-                '</td>';
-    $row .= '<td bgcolor="#FFFFE6">'.$part.'</td>' if ($show_part);
-    foreach ($num,$tries) {
-        $row .= '<td bgcolor="#EEFFCC" align="right">'.$_.'</td>';
-    }
-    foreach ($mod,$mean) {
-        $row .= '<td bgcolor="#DDFFFF" align="right">'.
-                  sprintf("%5.2f",$_).'</td>';
-    }
-    foreach ($Solved,$solved) {
-        $row .= '<td bgcolor="#DDFFFF" align="right">'.$_.'</td>';
-    }
-    foreach ($wrongpercent) {
-        $row .= '<td bgcolor="#DDFFFF" align="right">'.
-                  sprintf("%5.1f",$_).'</td>';
-    }
-    foreach ($DegOfDiff,$STD,$SKEW) {
-        $row .= '<td bgcolor="#FFDDDD" align="right">'.
-                  sprintf("%5.2f",$_).'</td>';
+sub compute_discrimination_factor {
+    my ($resource,$part,$seq) = @_;
+    my $symb = $resource->symb;
+    my @Resources;
+    foreach my $res (&Apache::lonstathelpers::get_resources($navmap,$seq)){
+        next if ($res->symb eq $symb);
+        push (@Resources,$res->symb);
+    }
+    #
+    # rank
+    my ($starttime,$endtime) = &Apache::lonstathelpers::get_time_limits();
+    my $ranking = 
+        &Apache::loncoursedata::rank_students_by_scores_on_resources
+        (\@Resources,
+         [&Apache::lonstatistics::get_selected_sections()],
+         [&Apache::lonstatistics::get_selected_groups()],
+         $Apache::lonstatistics::enrollment_status,undef,
+         $starttime,$endtime, $symb);
+    #
+    # compute their percent scores on the problems in the sequence,
+    my $number_to_grab = int(scalar(@{$ranking})/4);
+    my $num_students = scalar(@{$ranking});
+    my @BottomSet = map { $_->[&Apache::loncoursedata::RNK_student()]; 
+                      } @{$ranking}[0..$number_to_grab];
+    my @TopSet    = 
+        map { 
+            $_->[&Apache::loncoursedata::RNK_student()]; 
+          } @{$ranking}[-$number_to_grab..0];
+    if (! @BottomSet || (@BottomSet == 1 && $BottomSet[0] eq '') ||
+        ! @TopSet    || (@TopSet    == 1 && $TopSet[0]    eq '')) {
+        return 'nan';
+    }
+    my ($bottom_sum,$bottom_max) = 
+        &Apache::loncoursedata::get_sum_of_scores($symb,$part,\@BottomSet,
+                                                  undef,$starttime,$endtime);
+    my ($top_sum,$top_max) = 
+        &Apache::loncoursedata::get_sum_of_scores($symb,$part,\@TopSet,
+                                                  undef,$starttime,$endtime);
+    my $deg_of_disc;
+    if ($top_max == 0 || $bottom_max==0) {
+        $deg_of_disc = 'nan';
+    } else {
+        $deg_of_disc = ($top_sum/$top_max) - ($bottom_sum/$bottom_max);
     }
-    return $row;
+    #&Apache::lonnet::logthis('    '.$top_sum.'/'.$top_max.
+    #                         ' - '.$bottom_sum.'/'.$bottom_max);
+    return $deg_of_disc;
 }
 
-
 ###############################################
 ###############################################
-
-sub BuildGraphicChart {
-    my ($graph,$cacheDB,$courseDescription,$students,$courseID,$r,$c)=@_;
-    my %cache;
-    my $max;
-    my $title = '';
-    if($graph eq 'DoDiffGraph') {
-	$title = 'Degree-of-Difficulty';
+##
+## Compute KR-21
+##
+## To compute KR-21, you need the following information:
+##
+## K=the number of items in your test
+## M=the mean score on the test
+## s=the standard deviation of the scores on your test 
+##
+## then:
+## 
+## KR-21 rk= [K/(K-1)] * [1- (M*(K-M))/(K*s^2))]
+##
+###############################################
+###############################################
+sub compute_sequence_statistics {
+    my ($seq) = @_;
+    my $symb = $seq->symb;
+    my @Resources;
+    my $part_count;
+    foreach my $res (&Apache::lonstathelpers::get_resources($navmap,$seq)) {
+        push (@Resources,$res->symb);
+        $part_count += scalar(@{$res->parts});
+    }
+    my ($starttime,$endtime) = &Apache::lonstathelpers::get_time_limits();
+    #
+    # First compute statistics based on student scores
+    my ($smin,$smax,$sMean,$sSTD,$scount,$sMAX) = 
+        &Apache::loncoursedata::score_stats
+                    ([&Apache::lonstatistics::get_selected_sections()],
+                     [&Apache::lonstatistics::get_selected_groups()],
+                     $Apache::lonstatistics::enrollment_status,
+                     \@Resources,$starttime,$endtime,undef);
+    $SeqStat{$symb}->{'title'}  = $seq->compTitle;
+    $SeqStat{$symb}->{'scoremax'}  = $smax;
+    $SeqStat{$symb}->{'scoremin'}  = $smin;
+    $SeqStat{$symb}->{'scoremean'} = $sMean;
+    $SeqStat{$symb}->{'scorestd'}  = $sSTD;
+    $SeqStat{$symb}->{'scorecount'} = $scount;
+    $SeqStat{$symb}->{'max_possible'} = $sMAX;
+    #
+    # Compute statistics based on the number of correct problems
+    # 'correct' is taken to mean 
+    my ($cmin,$cmax,$cMean,$cSTD,$ccount)=
+        &Apache::loncoursedata::count_stats
+        ([&Apache::lonstatistics::get_selected_sections()],
+         [&Apache::lonstatistics::get_selected_groups()],
+         $Apache::lonstatistics::enrollment_status,
+         \@Resources,$starttime,$endtime,undef);
+    my $K = $part_count;
+    my $kr_21;
+    if ($K > 1 && $cSTD > 0) {
+        $kr_21 =  ($K/($K-1)) * (1 - $cMean*($K-$cMean)/($K*$cSTD**2));
     } else {
-	$title = 'Wrong-Percentage';
-    }
-    my $currentSequence = -1;
-    my $sortProblems = 'Sort Within Sequence';
-    my ($result, $orderedProblems) =
-        &InitializeProblemStatistics($cacheDB, $students, $courseID, $c, $r);
-    if($result ne 'OK') {
-        return;
+        $kr_21 = 'nan';
     }
-    my @values = ();
-    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER(),0640)) {
-        return 'Unable to tie database.7';
-    }
-    foreach(@$orderedProblems) {
-        my ($sequence,$problem,$part)=split(':', $_);
-        if($cache{'StatisticsMaps'} ne 'All Maps'  &&
-           $cache{'StatisticsMaps'} ne $cache{$sequence.':title'}) {
-             next;
-        }
-        if( $currentSequence == -1 ||
-            ($sortProblems eq 'Sort Within Sequence' &&
-            $currentSequence != $sequence)) {
-	    if($currentSequence != -1) {
-		&DrawGraph(\@values,$courseDescription,$title,$max,$r);
-	    }
-            if($sortProblems eq 'Sort Within Sequence') {
-                $r->print('<br><b>'.$cache{$sequence.':title'}.'</b>'."\n");
-            }
-            $currentSequence = $sequence;
-            @values = ();
-	    $max=0;
-        }
-        my $data = 0;
-        if($graph eq 'DoDiffGraph') {
-            $data = sprintf("%.2f", $cache{$_.':degreeOfDifficulty'}),
-        } else {
-            $data = sprintf("%.1f", $cache{$_.':percentWrong'}),
-        }
-        if($max < $data) {
-            $max = $data;
-        }
-        push(@values, $data);
-    }
-    untie(%cache);
-    &DrawGraph(\@values,$courseDescription,$title,$max,$r);
+    $SeqStat{$symb}->{'countmax'} = $cmax;
+    $SeqStat{$symb}->{'countmin'} = $cmin;
+    $SeqStat{$symb}->{'countstd'} = $cSTD;
+    $SeqStat{$symb}->{'countmean'} = $cMean;
+    $SeqStat{$symb}->{'count'} = $ccount;
+    $SeqStat{$symb}->{'items'} = $K;
+    $SeqStat{$symb}->{'KR-21'}=$kr_21;
     return;
 }
 
-sub DrawGraph {
-    my ($values,$courseDescription,$title,$Max,$r)=@_;
-    my $sendValues = join(',', @$values);
-    my $sendCount = scalar(@$values);
-    $r->print("<br>The Maximum Value is: $Max");
-    if ( $Max > 1 ) {
-	if ($Max % 10) {
-            if ( int($Max) < $Max ) {
-	    	$Max++;
-		$Max = int($Max);
-	    }
-	}
-    #(10 - $Max % 10);
-    } else { $Max = 1; }
-    my @GData = ('','Problem_number',$title,$Max,$sendCount,$sendValues);
-#    $r->print('</form>'."\n");
-    $r->print('<br>'."\n");
-    $r->print('<IMG src="/cgi-bin/graph.png?'.
-              (join('&', @GData)).'" border="1" />');
-#    $r->print('<form>'."\n");
-    $r->print('<br>'."\n");
-}
-
-#---- Problem Statistics Web Page ---------------------------------------
-sub CreateProblemStatisticsTableHeading {
-    my ($headings,$r)=@_;
-    my $Str='';
-    $Str .= '<tr>'."\n";
-    $Str .= '<th bgcolor="#ffffe6">P#</th>'."\n";
-    foreach(@$headings) {
-	$Str .= '<th bgcolor="#ffffe6">';
-        $Str .= '<a href="/adm/statistics?reportSelected=';
-        $Str .= &Apache::lonnet::escape('Problem Statistics');
-        $Str .= '&ProblemStatisticsSort=';
-        $Str .= &Apache::lonnet::escape($_).'">'.$_.'</a>&nbsp</th>'."\n";
-    }
-    $Str .= "\n".'</tr>'."\n";
-    return $Str;
-}
 
-sub BuildStatisticsTable {
-    my ($cache,$displayFormat,$sortProblems,$orderedProblems,$headings,
-        $r,$color)=@_;
-    my $count = 1;
-    my $currentSequence = -1;
-    foreach(@$orderedProblems) {
-        my ($sequence,$problem,$part)=split(':', $_);
-        if($cache->{'StatisticsMaps'} ne 'All Maps'  &&
-           $cache->{'StatisticsMaps'} ne $cache->{$sequence.':title'}) {
-            next;
-        }
-        if($currentSequence == -1 ||
-           ($sortProblems eq 'Sort Within Sequence' &&
-            $currentSequence != $sequence)) {
-            if($displayFormat ne 'Display CSV Format') {
-                if($currentSequence ne -1) {
-                    $r->print('</table>');
-                    $r->print('</td></tr></table><br>');
-                }
-                if($sortProblems eq 'Sort Within Sequence') {
-                    $r->print('<b>'.$cache->{$sequence.':title'}.'</b>');
-                }
-                $r->print('<table border="0"><tr><td bgcolor="#777777">'."\n");
-                $r->print('<table border="0" cellpadding="3">'."\n");
-                $r->print(&CreateProblemStatisticsTableHeading($headings, $r));
-            } else {
-                if($sortProblems eq 'Sort Within Sequence') {
-                    $r->print('"'.$cache->{$sequence.':title'}.'"');
-                }
-                $r->print('<br>');
-            }
-            $currentSequence = $sequence;
-        }
-        my $ref = '<a href="'.$cache->{$problem.':source'}.
-                  '" target="_blank">'.$cache->{$problem.':title'}.'</a>';
-        my $title = $cache->{$problem.':title'};
-        if($part != 0) {
-            $title .= ' Part '.$part;
-        }
-        my $source = $cache->{$problem.':source'};
-        my $tableData = join('&', $ref, $title, $source,
-                       $cache->{$_.':studentCount'},
-                       $cache->{$_.':totalTries'},
-                       $cache->{$_.':maxTries'},
-                       $cache->{$_.':mean'},
-                       $cache->{$_.':correct'},
-                       $cache->{$_.':correctByOverride'},
-                       $cache->{$_.':percentWrong'},
-                       $cache->{$_.':degreeOfDifficulty'},
-                       $cache->{$_.':standardDeviation'},
-                       $cache->{$_.':skewness'},
-                       $cache->{$_.':discriminationFactor1'},
-                       $cache->{$_.':discriminationFactor2'});
-        &TableRow($displayFormat,$tableData,$count,$r,$color);
-        $count++;
-    }
-    if($displayFormat ne 'Display CSV Format') {
-        $r->print('</table>'."\n");
-        $r->print('</td></tr></table>');
-    } else {
-        $r->print('<br>');
-    }
-    return;
-}
 
-sub TableRow {
-    my ($displayFormat,$Str,$RealIdx,$r,$color)=@_;
-    my($ref,$title,$source,$StdNo,$TotalTries,$MxTries,$Avg,$YES,$Override,
-       $Wrng,$DoD,$SD,$Sk,$_D1,$_D2)=split(/\&/,$Str);	
-    my $Ptr;
-    if($displayFormat eq 'Display CSV Format') {
-        $Ptr='"'.$RealIdx.'",'."\n".
-             '"'.$title.'",'."\n".
-             '"'.$source.'",'."\n".
-             '"'.$StdNo.'",'."\n".
-             '"'.$TotalTries.'",'."\n".
-             '"'.$MxTries.'",'."\n".
-             '"'.$Avg.'",'."\n".
-             '"'.$YES.'",'."\n".
-             '"'.$Override.'",'."\n".
-             '"'.$Wrng.'",'."\n".
-             '"'.$DoD.'",'."\n".
-             '"'.$SD.'",'."\n".
-             '"'.$Sk.'",'."\n".
-             '"'.$_D1.'",'."\n".
-             '"'.$_D2.'"'."\n".
-             "<br>\n";
-        $r->print("\n".$Ptr);
-    } else {
-        $Ptr='<tr>'."\n".
-             '<td bgcolor="#ffffe6">'.$RealIdx.'</td>'."\n".
-             '<td bgcolor="#ffffe6">'.$ref.'</td>'."\n".
-             '<td bgcolor='.$color->{"yellow"}.'> '.$StdNo.'</td>'."\n".
-             '<td bgcolor='.$color->{"yellow"}.'>'.$TotalTries.'</td>'."\n".
-             '<td bgcolor='.$color->{"yellow"}.'>'.$MxTries.'</td>'."\n".
-             '<td bgcolor='.$color->{"gb"}.'>'.$Avg.'</td>'."\n".
-             '<td bgcolor='.$color->{"gb"}.'> '.$YES.'</td>'."\n".
-             '<td bgcolor='.$color->{"gb"}.'> '.$Override.'</td>'."\n".
-             '<td bgcolor='.$color->{"red"}.'> '.$Wrng.'</td>'."\n".
-             '<td bgcolor='.$color->{"red"}.'> '.$DoD.'</td>'."\n".
-             '<td bgcolor='.$color->{"green"}.'> '.$SD.'</td>'."\n".
-             '<td bgcolor='.$color->{"green"}.'> '.$Sk.'</td>'."\n".
-             '<td bgcolor='.$color->{"purple"}.'> '.$_D1.'</td>'."\n".
-	     '<td bgcolor='.$color->{"purple"}.'> '.$_D2.'</td>'."\n";
-        $r->print($Ptr.'</tr>'."\n");
-    }
-    return;
-}
+=pod 
 
-# For loading the colored table for display or un-colored for print
-sub setbgcolor {
-    my $PrintTable=shift;
-    my %color;
-    if ($PrintTable){
-	$color{"gb"}="#FFFFFF";
-	$color{"red"}="#FFFFFF";
-	$color{"yellow"}="#FFFFFF";
-	$color{"green"}="#FFFFFF";
-	$color{"purple"}="#FFFFFF";
-    } else {
-	$color{"gb"}="#DDFFFF";
-	$color{"red"}="#FFDDDD";
-	$color{"yellow"}="#EEFFCC";
-	$color{"green"}="#DDFFDD";
-	$color{"purple"}="#FFDDFF";
-    }
-    return \%color;
-}
-
-sub ProblemStatisticsButtons {
-    my ($displayFormat, $displayLegend, $sortProblems)=@_;
-    my $Ptr = '<tr><td></td><td align="left">';
-    $Ptr .= '<input type="submit" name="DoDiffGraph" ';
-    $Ptr .= 'value="Plot Degree of Difficulty" />'."\n";
-    $Ptr .= '</td><td align="left">';
-    $Ptr .= '<input type="submit" name="PercentWrongGraph" ';
-    $Ptr .= 'value="Plot Percent Wrong" />'."\n";
-    $Ptr .= '</td></tr><tr><td></td><td>'."\n";
-    $Ptr .= '<input type="submit" name="SortProblems" ';
-    if($sortProblems eq 'Sort All Problems') {
-        $Ptr .= 'value="Sort Within Sequence" />'."\n";
-    } else {
-        $Ptr .= 'value="Sort All Problems" />'."\n";
-    }
-    $Ptr .= '</td><td align="left">';
-    $Ptr .= '<input type="submit" name="DisplayLegend" ';
-    if($displayLegend eq 'Show Legend') {
-        $Ptr .= 'value="Hide Legend" />'."\n";
-    } else {
-        $Ptr .= 'value="Show Legend" />'."\n";
-    }
-    $Ptr .= '</td><td align="left">';
-    $Ptr .= '<input type="submit" name="DisplayCSVFormat" ';
-    if($displayFormat eq 'Display CSV Format') {
-        $Ptr .= 'value="Display Table Format" />'."\n";
-    } else {
-        $Ptr .= 'value="Display CSV Format" />'."\n";
-    }
-    $Ptr .= '</td></tr>';
-    return $Ptr;
-}
+=item ProblemStatisticsLegend
 
-sub ProblemStatisticsLegend {
-    my $Ptr = '';
-    $Ptr = '<table border="0">';
-    $Ptr .= '<tr><td>';
-    $Ptr .= '<b>#Stdnts</b></td>';
-    $Ptr .= '<td>Total number of students attempted the problem.';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>Tries</b></td>';
-    $Ptr .= '<td>Total number of tries for solving the problem.';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>Mod</b></td>';
-    $Ptr .= '<td>Largest number of tries for solving the problem by a student.';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>Mean</b></td>';
-    $Ptr .= '<td>Average number of tries. [ Tries / #Stdnts ]';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>#YES</b></td>';
-    $Ptr .= '<td>Number of students solved the problem correctly.';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>#yes</b></td>';
-    $Ptr .= '<td>Number of students solved the problem by override.';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>%Wrong</b></td>';
-    $Ptr .= '<td>Percentage of students who tried to solve the problem ';
-    $Ptr .= 'but is still incorrect. [ 100*((#Stdnts-(#YES+#yes))/#Stdnts) ]';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>DoDiff</b></td>';
-    $Ptr .= '<td>Degree of Difficulty of the problem.  ';
-    $Ptr .= '[ 1 - ((#YES+#yes) / Tries) ]';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>S.D.</b></td>';
-    $Ptr .= '<td>Standard Deviation of the tries.  ';
-    $Ptr .= '[ sqrt(sum((Xi - Mean)^2)) / (#Stdnts-1) ';
-    $Ptr .= 'where Xi denotes every student\'s tries ]';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>Skew.</b></td>';
-    $Ptr .= '<td>Skewness of the students tries.';
-    $Ptr .= '[(sqrt( sum((Xi - Mean)^3) / #Stdnts)) / (S.D.^3)]';
-    $Ptr .= '</td></tr><tr><td>';
-    $Ptr .= '<b>Dis.F.</b></td>';
-    $Ptr .= '<td>Discrimination Factor: A Standard for evaluating the ';
-    $Ptr .= 'problem according to a Criterion<br>';
-    $Ptr .= '<b>[Criterion to group students into %27 Upper Students - ';
-    $Ptr .= 'and %27 Lower Students]</b><br>';
-    $Ptr .= '<b>1st Criterion</b> for Sorting the Students: ';
-    $Ptr .= '<b>Sum of Partial Credit Awarded / Total Number of Tries</b><br>';
-    $Ptr .= '<b>2nd Criterion</b> for Sorting the Students: ';
-    $Ptr .= '<b>Total number of Correct Answers / Total Number of Tries</b>';
-    $Ptr .= '</td></tr>';
-    $Ptr .= '<tr><td><b>Disc.</b></td>';
-    $Ptr .= '<td>Number of Students had at least one discussion.';
-    $Ptr .= '</td></tr></table>';
-    return $Ptr;
-}
+=over 4
+
+=item #Stdnts
+Total number of students attempted the problem.
+
+=item Tries
+Total number of tries for solving the problem.
+
+=item Max Tries
+Largest number of tries for solving the problem by a student.
+
+=item Mean
+Average number of tries. [ Tries / #Stdnts ]
+
+=item #YES
+Number of students solved the problem correctly.
+
+=item #yes
+Number of students solved the problem by override.
+
+=item %Wrong
+Percentage of students who tried to solve the problem 
+but is still incorrect. [ 100*((#Stdnts-(#YES+#yes))/#Stdnts) ]
+
+=item DoDiff
+Degree of Difficulty of the problem.  
+[ 1 - ((#YES+#yes) / Tries) ]
+
+=item S.D.
+Standard Deviation of the tries.  
+[ sqrt(sum((Xi - Mean)^2)) / (#Stdnts-1) 
+where Xi denotes every student\'s tries ]
+
+=item Skew.
+Skewness of the students tries.
+[(sqrt( sum((Xi - Mean)^3) / #Stdnts)) / (S.D.^3)]
+
+=item Dis.F.
+Discrimination Factor: A Standard for evaluating the 
+problem according to a Criterion<br>
+
+=item [Criterion to group students into %27 Upper Students - 
+and %27 Lower Students]
+1st Criterion for Sorting the Students: 
+Sum of Partial Credit Awarded / Total Number of Tries
+2nd Criterion for Sorting the Students: 
+Total number of Correct Answers / Total Number of Tries
+
+=item Disc.
+Number of Students had at least one discussion.
+
+=back
+
+=cut
 
-#---- END Problem Statistics Web Page ----------------------------------------
+############################################################
+############################################################
 
 1;
 __END__