function workshop_grade_assessments($workshop, $verbose = false)
{
global $WORKSHOP_EWEIGHTS;
// timeout after 10 minutes
@set_time_limit(600);
$timenow = time();
// set minumim value for the variance (of the elements)
$minvar = 0.05;
// check when the standard deviations were calculated
$oldtotalassessments = get_field("workshop_elements", "totalassessments", "workshopid", $workshop->id, "elementno", 0);
$totalassessments = count_records("workshop_assessments", "workshopid", $workshop->id);
// calculate the std. devs every 10 assessments for low numbers of assessments, thereafter every 100 new assessments
if ($totalassessments < 100 and $totalassessments - $oldtotalassessments > 10 or $totalassessments - $oldtotalassessments > 100) {
// calculate the means for each submission using just the "good" assessments
if ($submissions = get_records("workshop_submissions", "workshopid", $workshop->id)) {
foreach ($submissions as $submission) {
$nassessments[$submission->id] = 0;
if ($assessments = workshop_get_assessments($submission)) {
foreach ($assessments as $assessment) {
// test if assessment is "good", a teacher assessment always "good", but may be weighted out
if (workshop_is_teacher($workshop, $assessment->userid)) {
if (!$workshop->teacherweight) {
// drop teacher's assessment as weight is zero
continue;
}
} elseif (!$assessment->gradinggrade and $assessment->timegraded or $workshop->agreeassessments and !$assessment->timeagreed) {
// it's a duff assessment, or it's not been agreed
continue;
}
if (isset($num[$submission->id])) {
if (workshop_is_teacher($workshop, $assessment->userid)) {
$num[$submission->id] += $workshop->teacherweight;
// weight teacher's assessment
} else {
$num[$submission->id]++;
// number of assessments
}
$nassessments[$submission->id]++;
} else {
if (workshop_is_teacher($workshop, $assessment->userid)) {
$num[$submission->id] = $workshop->teacherweight;
} else {
$num[$submission->id] = 1;
}
$nassessments[$submission->id] = 1;
}
for ($i = 0; $i < $workshop->nelements; $i++) {
$grade = get_field("workshop_grades", "grade", "assessmentid", $assessment->id, "elementno", $i);
if (isset($sum[$submission->id][$i])) {
if (workshop_is_teacher($workshop, $assessment->userid)) {
$sum[$submission->id][$i] += $workshop->teacherweight * $grade;
// teacher's grade
} else {
$sum[$submission->id][$i] += $grade;
// student's grade
}
} else {
if (workshop_is_teacher($workshop, $assessment->userid)) {
$sum[$submission->id][$i] = $workshop->teacherweight * $grade;
// teacher's grade
} else {
$sum[$submission->id][$i] = $grade;
// students's grade
}
}
}
}
}
}
if (!isset($num)) {
// no assessments yet
return;
}
reset($num);
// calculate the means for each submission
$total = 0;
foreach ($num as $submissionid => $n) {
if ($n) {
// stop division by zero
for ($i = 0; $i < $workshop->nelements; $i++) {
$mean[$submissionid][$i] = $sum[$submissionid][$i] / $n;
// echo "Submission: $submissionid; Element: $i; Mean: {$mean[$submissionid][$i]}<br />\n";
}
$total += $n;
// weighted total
}
}
if ($verbose) {
echo "<p style=\"text-align:center\">" . get_string("numberofsubmissions", "workshop", count($num)) . "<br />\n";
echo get_string("numberofassessmentsweighted", "workshop", $total) . "</p>\n";
}
// now get an estimate of the standard deviation of each element in the assessment
// this is just a rough measure, all assessments are included and teacher's assesments are not weighted
$n = 0;
for ($i = 0; $i < $workshop->nelements; $i++) {
$var[$i] = 0;
}
foreach ($submissions as $submission) {
if ($assessments = workshop_get_assessments($submission)) {
foreach ($assessments as $assessment) {
$n++;
for ($i = 0; $i < $workshop->nelements; $i++) {
$grade = get_field("workshop_grades", "grade", "assessmentid", $assessment->id, "elementno", $i);
$temp = $mean[$submission->id][$i] - $grade;
$var[$i] += $temp * $temp;
}
}
}
}
for ($i = 0; $i < $workshop->nelements; $i++) {
if ($n > 1) {
$sd[$i] = sqrt($var[$i] / ($n - 1));
} else {
$sd[$i] = 0;
}
set_field("workshop_elements", "stddev", $sd[$i], "workshopid", $workshop->id, "elementno", $i);
set_field("workshop_elements", "totalassessments", $totalassessments, "workshopid", $workshop->id, "elementno", $i);
if ($verbose) {
echo get_string("standarddeviationofelement", "workshop", $i + 1) . " {$sd[$i]}<br />";
if ($sd[$i] <= $minvar) {
print_string("standarddeviationnote", "workshop") . "<br />\n";
}
}
}
}
}
// this section looks at each submission if the number of assessments made has increased it recalculates the
// grading grades for those assessments
// first get the assignment elements for the weights and the stddevs...
if ($elementsraw = get_records("workshop_elements", "workshopid", $workshop->id, "elementno ASC")) {
foreach ($elementsraw as $element) {
$weight[] = $element->weight;
// to renumber index 0,1,2...
$sd[] = $element->stddev;
// to renumber index 0,1,2...
}
}
unset($num);
// may have been used in calculating stddevs
unset($sum);
// ditto
if ($submissions = get_records("workshop_submissions", "workshopid", $workshop->id)) {
foreach ($submissions as $submission) {
// see if the number of assessments has changed
$nassessments = workshop_count_assessments($submission);
if ($submission->nassessments != $nassessments) {
// ...if there are three or more assessments calculate the variance of each assessment.
// Use the variance to find the "best" assessment. (When there is only one or two assessments they
// are not altered by this routine.)
if ($verbose) {
echo "Processing submission {$submission->id} ({$nassessments} asessments)...\n";
}
if ($nassessments > 2) {
$num = 0;
// weighted number of assessments
for ($i = 0; $i < $workshop->nelements; $i++) {
$sum[$i] = 0;
// weighted sum of grades
}
if ($assessments = workshop_get_assessments($submission)) {
// first calculate the mean grades for each element
foreach ($assessments as $assessment) {
// test if assessment is "good", a teacher assessment always "good", but may be weighted out
if (workshop_is_teacher($workshop, $assessment->userid)) {
if (!$workshop->teacherweight) {
// drop teacher's assessment as weight is zero
continue;
}
} else {
if (!$assessment->gradinggrade and $assessment->timegraded or $workshop->agreeassessments and !$assessment->timeagreed) {
// it's a duff assessment, or it's not been agreed
continue;
}
}
if (workshop_is_teacher($workshop, $assessment->userid)) {
$num += $workshop->teacherweight;
// weight teacher's assessment
} else {
$num++;
// student assessment just add one
}
for ($i = 0; $i < $workshop->nelements; $i++) {
$grade = get_field("workshop_grades", "grade", "assessmentid", $assessment->id, "elementno", $i);
if (workshop_is_teacher($workshop, $assessment->userid)) {
$sum[$i] += $workshop->teacherweight * $grade;
// teacher's grade
} else {
$sum[$i] += $grade;
// student's grade
}
}
}
if ($num) {
// could all the assessments be duff?
for ($i = 0; $i < $workshop->nelements; $i++) {
$mean[$i] = $sum[$i] / $num;
if ($verbose) {
echo "Submission: {$submission->id}; Element: {$i}; Mean: {$mean[$i]}\n";
}
}
} else {
continue;
// move to the next submission
}
// run through the assessments again to see which is the "best" one (the one
// closest to the mean)
$lowest = 10000000000.0;
foreach ($assessments as $assessment) {
if ($workshop->agreeassessments and !$assessment->timeagreed) {
// ignore assessments that have not been agreed
continue;
}
$var = 0;
for ($i = 0; $i < $workshop->nelements; $i++) {
$grade = get_field("workshop_grades", "grade", "assessmentid", $assessment->id, "elementno", $i);
if ($sd[$i] > $minvar) {
$temp = ($mean[$i] - $grade) * $WORKSHOP_EWEIGHTS[$weight[$i]] / $sd[$i];
} else {
$temp = 0;
}
$var += $temp * $temp;
}
// find the "best" assessment of this submission
if ($lowest > $var) {
$lowest = $var;
$bestassessmentid = $assessment->id;
}
}
if (!($best = get_record("workshop_assessments", "id", $bestassessmentid))) {
notify("Workshop grade assessments: cannot find best assessment");
continue;
}
if ($verbose) {
echo "Best assessment is {$bestassessmentid};\n";
}
foreach ($assessments as $assessment) {
// don't overwrite teacher's grade
if ($assessment->teachergraded) {
continue;
}
if ($assessment->id == $bestassessmentid) {
// it's the best one, set the grading grade to the maximum
set_field("workshop_assessments", "gradinggrade", 100, "id", $assessment->id);
set_field("workshop_assessments", "timegraded", $timenow, "id", $assessment->id);
} else {
// it's one of the pack, compare with the best...
$gradinggrade = round(workshop_compare_assessments($workshop, $best, $assessment));
// ...and save the grade for the assessment
set_field("workshop_assessments", "gradinggrade", $gradinggrade, "id", $assessment->id);
set_field("workshop_assessments", "timegraded", $timenow, "id", $assessment->id);
}
}
}
} else {
// there are less than 3 assessments for this submission
if ($assessments = workshop_get_assessments($submission)) {
foreach ($assessments as $assessment) {
if (!$assessment->timegraded and !$assessment->teachergraded) {
// set the grading grade to the maximum and say it's been graded
set_field("workshop_assessments", "gradinggrade", 100, "id", $assessment->id);
set_field("workshop_assessments", "timegraded", $timenow, "id", $assessment->id);
}
}
}
}
// set the number of assessments for this submission
set_field("workshop_submissions", "nassessments", $nassessments, "id", $submission->id);
}
}
}
return;
}
foreach ($assessments as $studentassessment) {
// skip if it's not a student assessment
if (!workshop_is_student($workshop, $studentassessment->userid)) {
continue;
}
$gradinggrade = workshop_compare_assessments($workshop, $assessment, $studentassessment);
set_field("workshop_assessments", "timegraded", $timenow, "id", $studentassessment->id);
set_field("workshop_assessments", "gradinggrade", $gradinggrade, "id", $studentassessment->id);
}
}
} else {
//it's a student assessment, see if there's a corresponding teacher's assessment
if ($assessments = workshop_get_assessments($submission)) {
foreach ($assessments as $teacherassessment) {
if (workshop_is_teacher($workshop, $teacherassessment->userid)) {
$gradinggrade = workshop_compare_assessments($workshop, $assessment, $teacherassessment);
set_field("workshop_assessments", "timegraded", $timenow, "id", $assessment->id);
set_field("workshop_assessments", "gradinggrade", $gradinggrade, "id", $assessment->id);
break;
// only look for the first teacher assessment
}
}
}
}
}
// any comment?
if (!empty($form->generalcomment)) {
set_field("workshop_assessments", "generalcomment", clean_param($form->generalcomment, PARAM_CLEAN), "id", $assessment->id);
}
add_to_log($course->id, "workshop", "assess", "viewassessment.php?id={$cm->id}&aid={$assessment->id}", "{$assessment->id}", "{$cm->id}");
// set up return address
