File:
[LON-CAPA] /
loncom /
interface /
statistics /
lonproblemstatistics.pm
Revision
1.41:
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Tue Mar 25 23:00:40 2003 UTC (22 years, 1 month ago) by
matthew
Branches:
MAIN
CVS tags:
HEAD
Removed GDBM_File dependence.
Removed &InitializeProblemStatistics, &ExtractStudentData, &SortDivideByTries,
&SortProblems, and &CalculateStatistics.
Added: &CreateInterface and shamelessly ripped off &OutputDescriptions and
&CreateAndParseOutputSelect from lonstudentassessment.pm.
Added &Gather_Student_Data to ensure the student data is up to date.
Rewrote &BuildProblemStatisticsPage to call &CreateInterface,
&Gather_Student_Data, and the proper output functions.
Added &output_html_grouped_by_sequence
Added &output_html_ungrouped which is not fully implemented at this time.
# The LearningOnline Network with CAPA
#
# $Id: lonproblemstatistics.pm,v 1.41 2003/03/25 23:00:40 matthew Exp $
#
# Copyright Michigan State University Board of Trustees
#
# This file is part of the LearningOnline Network with CAPA (LON-CAPA).
#
# LON-CAPA is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# LON-CAPA is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with LON-CAPA; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
# /home/httpd/html/adm/gpl.txt
#
# http://www.lon-capa.org/
#
# (Navigate problems for statistical reports
#
###
package Apache::lonproblemstatistics;
use strict;
use Apache::lonnet();
use Apache::lonhtmlcommon;
use Apache::loncoursedata;
use Apache::lonstatistics;
#######################################################
#######################################################
sub CreateInterface {
my $Str = '';
$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 .= '</tr>'."\n";
#
$Str .= '<tr><td align="center">'."\n";
$Str .= &Apache::lonstatistics::SectionSelect('Section','multiple',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 .= '</td></tr>'."\n";
$Str .= '</table>'."\n";
return $Str;
}
#######################################################
#######################################################
=pod
=item &CreateAndParseOutputSelector()
=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',
},
);
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 CreateAndParseOutputSelector {
my $Str = '';
my $elementname = 'outputmode';
#
# 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};
}
}
#
# 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'};
}
#
# 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>";
}
$Str .= "\n</select>";
return $Str;
}
###############################################
###############################################
###############################################
###############################################
sub Gather_Student_Data {
my ($r) = @_;
my $c = $r->connection();
#
my @Sequences = &Apache::lonstatistics::Sequences_with_Assess();
#
my @Students = @Apache::lonstatistics::Students;
#
# Open the progress window
my %prog_state=&Apache::lonhtmlcommon::Create_PrgWin
($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');
}
&Apache::lonhtmlcommon::Close_PrgWin($r,\%prog_state);
$r->rflush();
}
###############################################
###############################################
###############################################
###############################################
sub BuildProblemStatisticsPage {
my ($r,$c)=@_;
#
$output_mode = 'html';
$show = 'grouped';
#
$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($ENV{'form.statsfirstcall'})) {
return;
}
#
&Gather_Student_Data($r);
#
#
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);
}
} else {
$r->print("<h1>Not implemented</h1>");
}
return;
}
sub output_html_grouped_by_sequence {
my ($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 $sequence (&Apache::lonstatistics::Sequences_with_Assess()) {
next if ($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'}}) {
if ($part == 0) {
$part = ' ';
}
my ($num,$tries,$mod,$mean,$Solved,$solved,$DegOfDiff,$STD,
$SKEW) = &Apache::loncoursedata::get_problem_statistics
(undef,$resource->{'symb'},$part,
$ENV{'request.course.id'});
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).
"</tr>\n");
}
}
$r->print("</table>\n");
$r->print("</td></tr></table>\n");
$r->rflush();
}
#
return;
}
###############################################
###############################################
###############################################
###############################################
sub output_html_ungrouped {
my ($r) = @_;
#
my $sortby = $ENV{'form.sortby'};
if (! defined($sortby) || $sortby eq '') {
$sortby = 'sequence';
}
#
my $show_container = 0;
#$r->print(&ProblemStatisticsLegend());
my @Header = ("Title","Part","#Stdnts","Tries","Mod",
"Mean","#YES","#yes","%Wrng","DoDiff",
"S.D.","Skew.");#,"D.F.1st","D.F.2nd");
# #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->print('<table border="0" cellpadding="3">'."\n");
my $Str = '';
foreach (@Header) {
$Str .= '<th>'.
'<a href="javascript:document.Statistics.sortby.value='."'$_'".
';document.Statistics.submit();">'.
$_.'</a></th>';
}
$r->print('<tr bgcolor="#FFFFE6">'.$Str."</tr>\n");
$r->rflush();
#
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,
$ENV{'request.course.id'});
if ($part == 0) {
$part = ' ';
}
my $wrongpercent = 0;
if (defined($num) && $num > 0) {
$wrongpercent=int(10*100*($num-$Solved+$solved)/$num)/10;
}
if ($show_container) {
$r->print('<tr>'.
'<td bgcolor="#FFFFE6">'.$sequence->{'title'}.
'</td>'.
&statistics_html_table_data
($resource,$part,$num,$tries,$mod,$mean,$Solved,
$solved,$wrongpercent,$DegOfDiff,$STD,$SKEW).
"</tr>\n");
} else {
$r->print('<tr>'.&statistics_html_table_data
($resource,$part,$num,$tries,$mod,$mean,$Solved,
$solved,$wrongpercent,$DegOfDiff,$STD,$SKEW).
"</tr>\n");
}
}
}
}
$r->print("</table>\n");
$r->print("</td></tr></table>\n");
$r->rflush();
#
return;
}
###############################################
###############################################
###############################################
###############################################
sub statistics_html_table_data {
my ($resource,$part,$num,$tries,$mod,$mean,$Solved,$solved,$wrongpercent,
$DegOfDiff,$STD,$SKEW) = @_;
my $row = '';
$row .= '<td bgcolor="#FFFFE6">'.
'<a href="'.$resource->{'src'}.'" target="_blank" >'.
$resource->{'title'}.'</a>'.
'</td>';
$row .= '<td bgcolor="#FFFFE6">'.$part.'</td>' if (defined($part));
foreach ($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>';
}
return $row;
}
###############################################
###############################################
sub BuildGraphicChart {
my ($graph,$cacheDB,$courseDescription,$students,$courseID,$r,$c)=@_;
my %cache;
my $max;
my $title = '';
if($graph eq 'DoDiffGraph') {
$title = 'Degree-of-Difficulty';
} 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;
}
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,$r);
return;
}
sub DrawGraph {
my ($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> </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;
}
# 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;
}
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;
}
#---- END Problem Statistics Web Page ----------------------------------------
1;
__END__
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