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MDL-15268 "Content for Quiz Statistics report table" know looping through all question grades fetched from the db to calculate position statistics.

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jamiesensei 2008-07-16 11:55:38 +00:00
parent 9faa5c4469
commit ea751786e0
3 changed files with 139 additions and 8 deletions
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115
mod/quiz/report/statistics/report.php
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@ -144,6 +144,7 @@ class quiz_statistics_report extends quiz_default_report {
}
$usingattempts->heading = get_string('statsfor', 'quiz_statistics', $usingattempts->attempts);
$s = $usingattempts->countrecs;
$sumgradesavg = $usingattempts->total / $usingattempts->countrecs;
}
} else {
$s = 0;
@ -243,11 +244,14 @@ class quiz_statistics_report extends quiz_default_report {
}
}
if ($s){
//CIC, ER and SE.
/* //CIC, ER and SE.
//http://docs.moodle.org/en/Development:Quiz_item_analysis_calculations_in_practise#CIC.2C_ER_and_SE
list($qsql, $sqlparams) = $DB->get_in_or_equal(array_keys($questions), SQL_PARAMS_NAMED);
$sqlparams += $qaparams;//put quiz id in at beginning of array
$qgradeavgsql = "SELECT qs.question, AVG(qs.grade) FROM " .
$qgradeavgsql = "SELECT qs.question, " .
"AVG(qs.grade) AS gradeaverage " .
"AVG(qa.sumgrades - qs.grade) AS sumgradeaverage " .
"FROM " .
"{question_sessions} qns, " .
"{question_states} qs, " .
$fromqa.' '.
@ -256,7 +260,7 @@ class quiz_statistics_report extends quiz_default_report {
'AND qs.question '.$qsql.' ' .
$usingattempts->sql.
'AND qns.newgraded = qs.id GROUP BY qs.question';
$qgradeavgs = $DB->get_records_sql_menu($qgradeavgsql, $sqlparams);
$qgradeavgs = $DB->get_records_sql($qgradeavgsql, $sqlparams);
$sum = 0;
$sql = 'SELECT COUNT(1) as s,' .
@ -283,13 +287,112 @@ class quiz_statistics_report extends quiz_default_report {
}
$sum += $fromdb->power2;
}
//Discrimination index
$sql = 'SELECT qs.id, ' .
'qs.question, ' .
'qa.sumgrades - qs.grade AS sum, ' .
'qs.grade ' .
'FROM ' .
'{question_sessions} qns, ' .
'{question_states} qs, '.
$fromqa.' '.
'WHERE ' .$whereqa.
'AND qns.attemptid = qa.uniqueid '.
$usingattempts->sql.
'AND qns.newgraded = qs.id';
$fromdbrs = $DB->get_recordset_sql($sql, $qaparams);
if ($fromdbrs === false){
print_error('errorpowerquestions', 'quiz_statistics');
}
foreach ($fromdbrs as $record){
}*/
$sql = 'SELECT qs.id, ' .
'qs.question, ' .
'qa.sumgrades, ' .
'qs.grade ' .
'FROM ' .
'{question_sessions} qns, ' .
'{question_states} qs, '.
$fromqa.' '.
'WHERE ' .$whereqa.
'AND qns.attemptid = qa.uniqueid '.
$usingattempts->sql.
'AND qns.newgraded = qs.id';
$fromdbrs = $DB->get_recordset_sql($sql, $qaparams);
if ($fromdbrs === false){
print_error('errorstatisticsquestions', 'quiz_statistics');
}
foreach (array_keys($questions) as $qid){
$questions[$qid]->s = 0;
$questions[$qid]->totalgrades = 0;
$questions[$qid]->totalothergrades = 0;
$questions[$qid]->gradevariancesum = 0;
$questions[$qid]->othergradevariancesum = 0;
$questions[$qid]->covariancesum = 0;
$questions[$qid]->covariancemaxsum = 0;
$questions[$qid]->covariancewithoverallgradesum = 0;
$questions[$qid]->gradearray = array();
$questions[$qid]->othergradesarray = array();
}
foreach ($fromdbrs as $record){
$questions[$record->question]->s++;
$questions[$record->question]->totalgrades += $record->grade;
$questions[$record->question]->totalothergrades += $record->sumgrades - $record->grade;
//need to sort these to calculate max covariance :
$questions[$record->question]->gradearray[] = $record->grade;
$questions[$record->question]->othergradesarray[] = $record->sumgrades - $record->grade;
}
foreach (array_keys($questions) as $qid){
$questions[$qid]->gradeaverage = $questions[$qid]->totalgrades / $s;
$questions[$qid]->facility = $questions[$qid]->gradeaverage / $questions[$qid]->grade;
$questions[$qid]->othergradeaverage = $questions[$qid]->totalothergrades / $s;
sort($questions[$qid]->gradearray, SORT_NUMERIC);
sort($questions[$qid]->othergradesarray, SORT_NUMERIC);
}
//go through the records one more time
foreach ($fromdbrs as $record){
$gradedifference = ($record->grade - $questions[$record->question]->gradeaverage);
$othergradedifference = (($record->sumgrades - $record->grade) - $questions[$record->question]->othergradeaverage);
$overallgradedifference = $record->sumgrades - $sumgradesavg;
$sortedgradedifference = (array_shift($questions[$qid]->gradearray) - $questions[$record->question]->gradeaverage);
$sortedothergradedifference = (array_shift($questions[$qid]->othergradesarray) - $questions[$record->question]->othergradeaverage);
$questions[$record->question]->gradevariancesum += pow($gradedifference,2);
$questions[$record->question]->othergradevariancesum += pow($othergradedifference,2);
$questions[$record->question]->covariancesum += $gradedifference * $othergradedifference;
$questions[$record->question]->covariancemaxsum += $sortedgradedifference * $sortedothergradedifference;
$questions[$record->question]->covariancewithoverallgradesum += $gradedifference * $overallgradedifference;
}
$sumofcovariancewithoverallgrade = 0;
$sumofgradevariance =0;
foreach (array_keys($questions) as $qid){
$questions[$qid]->gradevariance = $questions[$qid]->gradevariancesum / ($s -1);
$questions[$qid]->othergradevariance = $questions[$qid]->othergradevariancesum / ($s -1);
$questions[$qid]->covariance = $questions[$qid]->covariancesum / ($s -1);
$questions[$qid]->covariancemax = $questions[$qid]->covariancemaxsum / ($s -1);
$sumofgradevariance += $questions[$qid]->gradevariance;
$questions[$qid]->covariancewithoverallgrade = $questions[$qid]->covariancewithoverallgradesum / ($s-1);
$sumofcovariancewithoverallgrade += sqrt($questions[$qid]->covariancewithoverallgrade);
$questions[$qid]->sd = sqrt($questions[$qid]->gradevariancesum / ($s -1));
//avoid divide by zero
if (sqrt($questions[$qid]->gradevariance * $questions[$qid]->othergradevariance)){
$questions[$qid]->discriminationindex = 100*$questions[$qid]->covariance
/ sqrt($questions[$qid]->gradevariance * $questions[$qid]->othergradevariance);
} else {
$questions[$qid]->discriminationindex = '';
}
$questions[$qid]->discriminativeefficiency = 100*$questions[$qid]->covariance / $questions[$qid]->covariancemax;
}
foreach (array_keys($questions) as $qid){
$questions[$qid]->effectiveweight = 100 * sqrt($questions[$qid]->covariancewithoverallgrade)/$sumofcovariancewithoverallgrade;
}
}
if (!$table->is_downloading()){
if ($s>1){
$sumofvarianceforallpositions = $sum / ($s -1);
$p = count($qgradeavgs);//no of positions
$p = count($questions);//no of positions
if ($p > 1){
$cic = (100 * $p / ($p -1)) * (1 - ($sumofvarianceforallpositions/$k2));
$cic = (100 * $p / ($p -1)) * (1 - ($sumofgradevariance)/$k2);
$quizattsstatistics->data[] = array(get_string('cic', 'quiz_statistics'), number_format($cic, $quiz->decimalpoints).' %');
$errorratio = 100 * sqrt(1-($cic/100));
$quizattsstatistics->data[] = array(get_string('errorratio', 'quiz_statistics'), number_format($errorratio, $quiz->decimalpoints).' %');