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Merge branch 'MDL-41888-master' of git://github.com/jamiepratt/moodle

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This commit is contained in:
Sam Hemelryk
2013-09-30 10:38:11 +13:00
parent 6b0b05b32f 522bef8030
commit 2f0a996b10
5 changed files with 506 additions and 329 deletions
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mod/quiz/report/statistics/classes/calculated.php
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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle 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 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* The statistics calculator returns an instance of this class which contains the calculated statistics.
*
* These quiz statistics calculations are described here :
*
* http://docs.moodle.org/dev/Quiz_statistics_calculations#Test_statistics
*
* @package quiz_statistics
* @copyright 2013 The Open University
* @author James Pratt [email protected]
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class quiz_statistics_calculated {
public function __construct($allattempts = null) {
if ($allattempts !== null) {
$this->allattempts = $allattempts;
}
}
/**
* @var bool whether we are calculating calculate stats from all attempts.
*/
public $allattempts;
/* Following stats all described here : http://docs.moodle.org/dev/Quiz_statistics_calculations#Test_statistics */
public $firstattemptscount = 0;
public $allattemptscount = 0;
public $firstattemptsavg;
public $allattemptsavg;
public $median;
public $standarddeviation;
public $skewness;
public $kurtosis;
public $cic;
public $errorratio;
public $standarderror;
/**
* @var int time these stats where calculated and cached.
*/
public $timemodified;
public function s() {
if ($this->allattempts) {
return $this->allattemptscount;
} else {
return $this->firstattemptscount;
}
}
public function avg() {
if ($this->allattempts) {
return $this->allattemptsavg;
} else {
return $this->firstattemptsavg;
}
}
/**
* @param $course
* @param $cm
* @param $quiz
* @return array to display in table or spreadsheet.
*/
public function get_formatted_quiz_info_data($course, $cm, $quiz) {
// You can edit this array to control which statistics are displayed.
$todisplay = array('firstattemptscount' => 'number',
'allattemptscount' => 'number',
'firstattemptsavg' => 'summarks_as_percentage',
'allattemptsavg' => 'summarks_as_percentage',
'median' => 'summarks_as_percentage',
'standarddeviation' => 'summarks_as_percentage',
'skewness' => 'number_format',
'kurtosis' => 'number_format',
'cic' => 'number_format_percent',
'errorratio' => 'number_format_percent',
'standarderror' => 'summarks_as_percentage');
// General information about the quiz.
$quizinfo = array();
$quizinfo[get_string('quizname', 'quiz_statistics')] = format_string($quiz->name);
$quizinfo[get_string('coursename', 'quiz_statistics')] = format_string($course->fullname);
if ($cm->idnumber) {
$quizinfo[get_string('idnumbermod')] = $cm->idnumber;
}
if ($quiz->timeopen) {
$quizinfo[get_string('quizopen', 'quiz')] = userdate($quiz->timeopen);
}
if ($quiz->timeclose) {
$quizinfo[get_string('quizclose', 'quiz')] = userdate($quiz->timeclose);
}
if ($quiz->timeopen && $quiz->timeclose) {
$quizinfo[get_string('duration', 'quiz_statistics')] =
format_time($quiz->timeclose - $quiz->timeopen);
}
// The statistics.
foreach ($todisplay as $property => $format) {
if (!isset($this->$property) || !$format) {
continue;
}
$value = $this->$property;
switch ($format) {
case 'summarks_as_percentage':
$formattedvalue = quiz_report_scale_summarks_as_percentage($value, $quiz);
break;
case 'number_format_percent':
$formattedvalue = quiz_format_grade($quiz, $value) . '%';
break;
case 'number_format':
// 2 extra decimal places, since not a percentage,
// and we want the same number of sig figs.
$formattedvalue = format_float($value, $quiz->decimalpoints + 2);
break;
case 'number':
$formattedvalue = $value + 0;
break;
default:
$formattedvalue = $value;
}
$quizinfo[get_string($property, 'quiz_statistics', $this->using_attempts_string())] = $formattedvalue;
}
return $quizinfo;
}
/**
* @return string the appropriate lang string to describe this option.
*/
protected function using_attempts_string() {
if ($this->allattempts) {
return get_string('allattempts', 'quiz_statistics');
} else {
return get_string('firstattempts', 'quiz_statistics');
}
}
/**
* @var array of names of properties of this class that are cached in db record.
*/
protected $fieldsindb = array('allattempts', 'firstattemptscount', 'allattemptscount', 'firstattemptsavg', 'allattemptsavg',
'median', 'standarddeviation', 'skewness',
'kurtosis', 'cic', 'errorratio', 'standarderror');
/**
* Cache the stats contained in this class.
*
* @param $qubaids qubaid_condition
*/
public function cache($qubaids) {
global $DB;
$toinsert = new stdClass();
foreach ($this->fieldsindb as $field) {
$toinsert->{$field} = $this->{$field};
}
$toinsert->hashcode = $qubaids->get_hash_code();
$toinsert->timemodified = time();
// Fix up some dodgy data.
if (isset($toinsert->errorratio) && is_nan($toinsert->errorratio)) {
$toinsert->errorratio = null;
}
if (isset($toinsert->standarderror) && is_nan($toinsert->standarderror)) {
$toinsert->standarderror = null;
}
// Store the data.
$DB->insert_record('quiz_statistics', $toinsert);
}
/**
* Given a record from 'quiz_statistics' table load the data into the properties of this class.
*
* @param $record from db.
*/
public function populate_from_record($record) {
foreach ($this->fieldsindb as $field) {
$this->$field = $record->$field;
}
$this->timemodified = $record->timemodified;
}
}
mod/quiz/report/statistics/classes/calculator.php
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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle 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 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Class to calculate and also manage caching of quiz statistics.
*
* These quiz statistics calculations are described here :
*
* http://docs.moodle.org/dev/Quiz_statistics_calculations#Test_statistics
*
* @package quiz_statistics
* @copyright 2013 The Open University
* @author James Pratt [email protected]
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class quiz_statistics_calculator {
/**
* Compute the quiz statistics.
*
* @param int $quizid the quiz id.
* @param int $currentgroup the current group. 0 for none.
* @param bool $useallattempts use all attempts, or just first attempts.
* @param array $groupstudents students in this group.
* @param int $p number of positions (slots).
* @param float $sumofmarkvariance sum of mark variance, calculated as part of question statistics
* @return array with two elements:
* - integer $s Number of attempts included in the stats.
* - object $quizstats The statistics for overall attempt scores.
*/
public function calculate($quizid, $currentgroup, $useallattempts, $groupstudents, $p, $sumofmarkvariance) {
$quizstats = $this->attempt_counts_and_averages($quizid, $currentgroup, $useallattempts, $groupstudents);
$s = $quizstats->s();
if ($s == 0) {
return $quizstats;
}
// Recalculate sql again this time possibly including test for first attempt.
list($fromqa, $whereqa, $qaparams) =
quiz_statistics_attempts_sql($quizid, $currentgroup, $groupstudents, $useallattempts);
$quizstats->median = $this->median($s, $fromqa, $whereqa, $qaparams);
if ($s > 1) {
$powers = $this->sum_of_powers_of_difference_to_mean($quizstats->avg(), $fromqa, $whereqa, $qaparams);
$quizstats->standarddeviation = sqrt($powers->power2 / ($s - 1));
// Skewness.
if ($s > 2) {
// See http://docs.moodle.org/dev/Quiz_item_analysis_calculations_in_practise#Skewness_and_Kurtosis.
$m2 = $powers->power2 / $s;
$m3 = $powers->power3 / $s;
$m4 = $powers->power4 / $s;
$k2 = $s * $m2 / ($s - 1);
$k3 = $s * $s * $m3 / (($s - 1) * ($s - 2));
if ($k2 != 0) {
$quizstats->skewness = $k3 / (pow($k2, 3 / 2));
// Kurtosis.
if ($s > 3) {
$k4 = $s * $s * ((($s + 1) * $m4) - (3 * ($s - 1) * $m2 * $m2)) / (($s - 1) * ($s - 2) * ($s - 3));
$quizstats->kurtosis = $k4 / ($k2 * $k2);
}
if ($p > 1) {
$quizstats->cic = (100 * $p / ($p -1)) * (1 - ($sumofmarkvariance / $k2));
$quizstats->errorratio = 100 * sqrt(1 - ($quizstats->cic / 100));
$quizstats->standarderror = $quizstats->errorratio *
$quizstats->standarddeviation / 100;
}
}
}
}
$quizstats->cache(quiz_statistics_qubaids_condition($quizid, $currentgroup, $groupstudents, $useallattempts));
return $quizstats;
}
/** @var integer Time after which statistics are automatically recomputed. */
const TIME_TO_CACHE = 900; // 15 minutes.
/**
* Load cached statistics from the database.
*
* @param $qubaids qubaid_condition
* @return quiz_statistics_calculated The statistics for overall attempt scores or false if not cached.
*/
public function get_cached($qubaids) {
global $DB;
$timemodified = time() - self::TIME_TO_CACHE;
$fromdb = $DB->get_record_select('quiz_statistics', 'hashcode = ? AND timemodified > ?',
array($qubaids->get_hash_code(), $timemodified));
$stats = new quiz_statistics_calculated();
$stats->populate_from_record($fromdb);
return $stats;
}
/**
* Find time of non-expired statistics in the database.
*
* @param $qubaids qubaid_condition
* @return integer|boolean Time of cached record that matches this qubaid_condition or false is non found.
*/
public function get_last_calculated_time($qubaids) {
global $DB;
$timemodified = time() - self::TIME_TO_CACHE;
return $DB->get_field_select('quiz_statistics', 'timemodified', 'hashcode = ? AND timemodified > ?',
array($qubaids->get_hash_code(), $timemodified));
}
/**
* Calculating count and mean of marks for first and ALL attempts by students.
*
* See : http://docs.moodle.org/dev/Quiz_item_analysis_calculations_in_practise
* #Calculating_MEAN_of_grades_for_all_attempts_by_students
* @param int $quizid
* @param int $currentgroup
* @param bool $useallattempts
* @param array $groupstudents
* @return quiz_statistics_calculated containing calculated counts, totals and averages.
*/
protected function attempt_counts_and_averages($quizid, $currentgroup, $useallattempts, $groupstudents) {
global $DB;
$quizstats = new quiz_statistics_calculated($useallattempts);
list($fromqa, $whereqa, $qaparams) = quiz_statistics_attempts_sql($quizid, $currentgroup, $groupstudents, true);
$attempttotals = $DB->get_records_sql("
SELECT
CASE WHEN attempt = 1 THEN 1 ELSE 0 END AS isfirst,
COUNT(1) AS countrecs,
SUM(sumgrades) AS total
FROM $fromqa
WHERE $whereqa
GROUP BY CASE WHEN attempt = 1 THEN 1 ELSE 0 END", $qaparams);
// Above query that returns sums and counts for first attempt and other non first attempts.
// We want to work out stats for first attempt or ALL attempts.
if (isset($attempttotals[1])) {
$quizstats->firstattemptscount = $attempttotals[1]->countrecs;
$firstattemptstotal = $attempttotals[1]->total;
} else {
$quizstats->firstattemptscount = 0;
$firstattemptstotal = 0;
}
if (isset($attempttotals[0])) {
$quizstats->allattemptscount = $quizstats->firstattemptscount + $attempttotals[0]->countrecs;
$allattemptstotal = $firstattemptstotal + $attempttotals[0]->total;
} else {
$quizstats->allattemptscount = $quizstats->firstattemptscount;
$allattemptstotal = $firstattemptstotal;
}
if ($quizstats->allattemptscount !== 0) {
$quizstats->allattemptsavg = $allattemptstotal / $quizstats->allattemptscount;
}
if ($quizstats->firstattemptscount !== 0) {
$quizstats->firstattemptsavg = $firstattemptstotal / $quizstats->firstattemptscount;
}
return $quizstats;
}
/**
* Median mark.
*
* http://docs.moodle.org/dev/Quiz_statistics_calculations#Median_Score
*
* @param $s integer count of attempts
* @param $fromqa string
* @param $whereqa string
* @param $qaparams string
* @return float
*/
protected function median($s, $fromqa, $whereqa, $qaparams) {
global $DB;
if ($s % 2 == 0) {
// An even number of attempts.
$limitoffset = $s / 2 - 1;
$limit = 2;
} else {
$limitoffset = floor($s / 2);
$limit = 1;
}
$sql = "SELECT id, sumgrades
FROM $fromqa
WHERE $whereqa
ORDER BY sumgrades";
$medianmarks = $DB->get_records_sql_menu($sql, $qaparams, $limitoffset, $limit);
return array_sum($medianmarks) / count($medianmarks);
}
/**
* Fetch the sum of squared, cubed and to the power 4 differences between sumgrade and it's mean.
*
* Explanation here : http://docs.moodle.org/dev/Quiz_item_analysis_calculations_in_practise
* #Calculating_Standard_Deviation.2C_Skewness_and_Kurtosis_of_grades_for_all_attempts_by_students
*
* @param $mean
* @param $fromqa
* @param $whereqa
* @param $qaparams
* @return object with properties power2, power3, power4
*/
protected function sum_of_powers_of_difference_to_mean($mean, $fromqa, $whereqa, $qaparams) {
global $DB;
$sql = "SELECT
SUM(POWER((quiza.sumgrades - $mean), 2)) AS power2,
SUM(POWER((quiza.sumgrades - $mean), 3)) AS power3,
SUM(POWER((quiza.sumgrades - $mean), 4)) AS power4
FROM $fromqa
WHERE $whereqa";
$params = array('mean1' => $mean, 'mean2' => $mean, 'mean3' => $mean) + $qaparams;
return $DB->get_record_sql($sql, $params, MUST_EXIST);
}
}
mod/quiz/report/statistics/report.php
+35 -324
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@@ -31,7 +31,6 @@ require_once($CFG->dirroot . '/mod/quiz/report/statistics/statistics_question_ta
require_once($CFG->dirroot . '/question/engine/statistics.php');
require_once($CFG->dirroot . '/question/engine/responseanalysis.php');
require_once($CFG->dirroot . '/mod/quiz/report/statistics/statisticslib.php');
/**
* The quiz statistics report provides summary information about each question in
* a quiz, compared to the whole quiz. It also provides a drill-down to more
@@ -41,8 +40,11 @@ require_once($CFG->dirroot . '/mod/quiz/report/statistics/statisticslib.php');
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class quiz_statistics_report extends quiz_default_report {
/** @var integer Time after which statistics are automatically recomputed. */
const TIME_TO_CACHE_STATS = 900; // 15 minutes.
/**
* @var context_module
*/
protected $context;
/** @var object instance of table class used for main questions stats table. */
protected $table;
@@ -127,15 +129,22 @@ class quiz_statistics_report extends quiz_default_report {
get_string('quizstructureanalysis', 'quiz_statistics'));
$questions = $this->load_and_initialise_questions_for_calculations($quiz);
// Get the data to be displayed.
list($quizstats, $questions, $subquestions, $s) =
$this->get_quiz_and_questions_stats($quiz, $currentgroup,
$nostudentsingroup, $useallattempts, $groupstudents, $questions);
$quizinfo = $this->get_formatted_quiz_info_data($course, $cm, $quiz, $quizstats);
if (!$nostudentsingroup) {
// Get the data to be displayed.
list($quizstats, $questions, $subquestions) =
$this->get_quiz_and_questions_stats($quiz, $currentgroup, $useallattempts, $groupstudents, $questions);
} else {
// Or create empty stats containers.
$quizstats = new quiz_statistics_calculated($useallattempts);
$qstats = new question_statistics($questions);
$questions = $qstats->questions;
$subquestions = $qstats->subquestions;
}
$quizinfo = $quizstats->get_formatted_quiz_info_data($course, $cm, $quiz);
// Set up the table, if there is data.
if ($s) {
$this->table->statistics_setup($quiz, $cm->id, $reporturl, $s);
if ($quizstats->s()) {
$this->table->statistics_setup($quiz, $cm->id, $reporturl, $quizstats->s());
}
// Print the page header stuff (if not downloading.
@@ -151,7 +160,7 @@ class quiz_statistics_report extends quiz_default_report {
if (!quiz_questions_in_quiz($quiz->questions)) {
echo quiz_no_questions_message($quiz, $cm, $this->context);
} else if (!$this->table->is_downloading() && $s == 0) {
} else if (!$this->table->is_downloading() && $quizstats->s() == 0) {
echo $OUTPUT->notification(get_string('noattempts', 'quiz'));
}
@@ -164,10 +173,10 @@ class quiz_statistics_report extends quiz_default_report {
// Overall report, then the analysis of each question.
$this->download_quiz_info_table($quizinfo);
if ($s) {
$this->output_quiz_structure_analysis_table($s, $questions, $subquestions);
if ($quizstats->s()) {
$this->output_quiz_structure_analysis_table($quizstats->s(), $questions, $subquestions);
if ($this->table->is_downloading() == 'xhtml' && $s != 0) {
if ($this->table->is_downloading() == 'xhtml' && $quizstats->s() != 0) {
$this->output_statistics_graph($quiz->id, $currentgroup, $useallattempts);
}
@@ -222,7 +231,7 @@ class quiz_statistics_report extends quiz_default_report {
} else if ($this->table->is_downloading()) {
// Downloading overview report.
$this->download_quiz_info_table($quizinfo);
$this->output_quiz_structure_analysis_table($s, $questions, $subquestions);
$this->output_quiz_structure_analysis_table($quizstats->s(), $questions, $subquestions);
$this->table->finish_output();
} else {
@@ -232,9 +241,9 @@ class quiz_statistics_report extends quiz_default_report {
$groupstudents, $useallattempts, $reporturl);
echo $this->everything_download_options();
echo $this->output_quiz_info_table($quizinfo);
if ($s) {
if ($quizstats->s()) {
echo $OUTPUT->heading(get_string('quizstructureanalysis', 'quiz_statistics'));
$this->output_quiz_structure_analysis_table($s, $questions, $subquestions);
$this->output_quiz_structure_analysis_table($quizstats->s(), $questions, $subquestions);
$this->output_statistics_graph($quiz->id, $currentgroup, $useallattempts);
}
}
@@ -433,73 +442,6 @@ class quiz_statistics_report extends quiz_default_report {
$this->table->finish_output(!$this->table->is_downloading());
}
protected function get_formatted_quiz_info_data($course, $cm, $quiz, $quizstats) {
// You can edit this array to control which statistics are displayed.
$todisplay = array('firstattemptscount' => 'number',
'allattemptscount' => 'number',
'firstattemptsavg' => 'summarks_as_percentage',
'allattemptsavg' => 'summarks_as_percentage',
'median' => 'summarks_as_percentage',
'standarddeviation' => 'summarks_as_percentage',
'skewness' => 'number_format',
'kurtosis' => 'number_format',
'cic' => 'number_format_percent',
'errorratio' => 'number_format_percent',
'standarderror' => 'summarks_as_percentage');
// General information about the quiz.
$quizinfo = array();
$quizinfo[get_string('quizname', 'quiz_statistics')] = format_string($quiz->name);
$quizinfo[get_string('coursename', 'quiz_statistics')] = format_string($course->fullname);
if ($cm->idnumber) {
$quizinfo[get_string('idnumbermod')] = $cm->idnumber;
}
if ($quiz->timeopen) {
$quizinfo[get_string('quizopen', 'quiz')] = userdate($quiz->timeopen);
}
if ($quiz->timeclose) {
$quizinfo[get_string('quizclose', 'quiz')] = userdate($quiz->timeclose);
}
if ($quiz->timeopen && $quiz->timeclose) {
$quizinfo[get_string('duration', 'quiz_statistics')] =
format_time($quiz->timeclose - $quiz->timeopen);
}
// The statistics.
foreach ($todisplay as $property => $format) {
if (!isset($quizstats->$property) || !$format) {
continue;
}
$value = $quizstats->$property;
switch ($format) {
case 'summarks_as_percentage':
$formattedvalue = quiz_report_scale_summarks_as_percentage($value, $quiz);
break;
case 'number_format_percent':
$formattedvalue = quiz_format_grade($quiz, $value) . '%';
break;
case 'number_format':
// 2 extra decimal places, since not a percentage,
// and we want the same number of sig figs.
$formattedvalue = format_float($value, $quiz->decimalpoints + 2);
break;
case 'number':
$formattedvalue = $value + 0;
break;
default:
$formattedvalue = $value;
}
$quizinfo[get_string($property, 'quiz_statistics',
$this->using_attempts_string(!empty($quizstats->allattempts)))] =
$formattedvalue;
}
return $quizinfo;
}
/**
* Output the table of overall quiz statistics.
* @param array $quizinfo as returned by {@link get_formatted_quiz_info_data()}.
@@ -566,222 +508,12 @@ class quiz_statistics_report extends quiz_default_report {
echo $output->graph($imageurl, $graphname);
}
/**
* Return the stats data for when there are no stats to show.
*
* @param int $firstattemptscount number of first attempts (optional).
* @param int $allattemptscount total number of attempts (optional).
* @return array with two elements:
* - integer $s Number of attempts included in the stats (0).
* - object $quizstats The statistics for overall attempt scores.
*/
protected function get_empty_stats($firstattemptscount = 0, $allattemptscount = 0) {
$quizstats = new stdClass();
$quizstats->firstattemptscount = $firstattemptscount;
$quizstats->allattemptscount = $allattemptscount;
return array(0, $quizstats);
}
/**
* Compute the quiz statistics.
*
* @param int $quizid the quiz id.
* @param int $currentgroup the current group. 0 for none.
* @param bool $useallattempts use all attempts, or just first attempts.
* @param array $groupstudents students in this group.
* @param int $p number of positions (slots).
* @param float $sumofmarkvariance sum of mark variance, calculated as part of question statistics
* @return array with two elements:
* - integer $s Number of attempts included in the stats.
* - object $quizstats The statistics for overall attempt scores.
*/
protected function calculate_quiz_stats($quizid, $currentgroup, $useallattempts, $groupstudents, $p, $sumofmarkvariance) {
global $DB;
// Calculating MEAN of marks for all attempts by students
// http://docs.moodle.org/dev/Quiz_item_analysis_calculations_in_practise
// #Calculating_MEAN_of_grades_for_all_attempts_by_students.
list($fromqa, $whereqa, $qaparams) = quiz_statistics_attempts_sql(
$quizid, $currentgroup, $groupstudents, true);
$attempttotals = $DB->get_records_sql("
SELECT
CASE WHEN attempt = 1 THEN 1 ELSE 0 END AS isfirst,
COUNT(1) AS countrecs,
SUM(sumgrades) AS total
FROM $fromqa
WHERE $whereqa
GROUP BY CASE WHEN attempt = 1 THEN 1 ELSE 0 END", $qaparams);
if (!$attempttotals) {
return $this->get_empty_stats();
}
if (isset($attempttotals[1])) {
$firstattempts = $attempttotals[1];
$firstattempts->average = $firstattempts->total / $firstattempts->countrecs;
} else {
$firstattempts = new stdClass();
$firstattempts->countrecs = 0;
$firstattempts->total = 0;
$firstattempts->average = null;
}
$allattempts = new stdClass();
if (isset($attempttotals[0])) {
$allattempts->countrecs = $firstattempts->countrecs + $attempttotals[0]->countrecs;
$allattempts->total = $firstattempts->total + $attempttotals[0]->total;
} else {
$allattempts->countrecs = $firstattempts->countrecs;
$allattempts->total = $firstattempts->total;
}
if ($useallattempts) {
$usingattempts = $allattempts;
$usingattempts->sql = '';
} else {
$usingattempts = $firstattempts;
$usingattempts->sql = 'AND quiza.attempt = 1 ';
}
$s = $usingattempts->countrecs;
if ($s == 0) {
return $this->get_empty_stats($firstattempts->countrecs, $allattempts->countrecs);
}
$quizstats = new stdClass();
$quizstats->allattempts = $useallattempts;
$quizstats->firstattemptscount = $firstattempts->countrecs;
$quizstats->allattemptscount = $allattempts->countrecs;
$quizstats->firstattemptsavg = $firstattempts->average;
$quizstats->allattemptsavg = $allattempts->total / $allattempts->countrecs;
// Recalculate sql again this time possibly including test for first attempt.
list($fromqa, $whereqa, $qaparams) = quiz_statistics_attempts_sql(
$quizid, $currentgroup, $groupstudents, $useallattempts);
// Median ...
if ($s % 2 == 0) {
// An even number of attempts.
$limitoffset = $s/2 - 1;
$limit = 2;
} else {
$limitoffset = floor($s/2);
$limit = 1;
}
$sql = "SELECT id, sumgrades
FROM $fromqa
WHERE $whereqa
ORDER BY sumgrades";
$medianmarks = $DB->get_records_sql_menu($sql, $qaparams, $limitoffset, $limit);
$quizstats->median = array_sum($medianmarks) / count($medianmarks);
if ($s > 1) {
// Fetch the sum of squared, cubed and power 4d
// differences between marks and mean mark.
$mean = $usingattempts->total / $s;
$sql = "SELECT
SUM(POWER((quiza.sumgrades - $mean), 2)) AS power2,
SUM(POWER((quiza.sumgrades - $mean), 3)) AS power3,
SUM(POWER((quiza.sumgrades - $mean), 4)) AS power4
FROM $fromqa
WHERE $whereqa";
$params = array('mean1' => $mean, 'mean2' => $mean, 'mean3' => $mean)+$qaparams;
$powers = $DB->get_record_sql($sql, $params, MUST_EXIST);
// Standard_Deviation:
// see http://docs.moodle.org/dev/Quiz_item_analysis_calculations_in_practise
// #Standard_Deviation.
$quizstats->standarddeviation = sqrt($powers->power2 / ($s - 1));
// Skewness.
if ($s > 2) {
// See http://docs.moodle.org/dev/
// Quiz_item_analysis_calculations_in_practise#Skewness_and_Kurtosis.
$m2= $powers->power2 / $s;
$m3= $powers->power3 / $s;
$m4= $powers->power4 / $s;
$k2= $s*$m2/($s-1);
$k3= $s*$s*$m3/(($s-1)*($s-2));
if ($k2) {
$quizstats->skewness = $k3 / (pow($k2, 3/2));
}
// Kurtosis.
if ($s > 3) {
$k4= $s*$s*((($s+1)*$m4)-(3*($s-1)*$m2*$m2))/(($s-1)*($s-2)*($s-3));
if ($k2) {
$quizstats->kurtosis = $k4 / ($k2*$k2);
}
}
}
}
if ($s > 1) {
if ($p > 1 && isset($k2)) {
$quizstats->cic = (100 * $p / ($p -1)) *
(1 - ($sumofmarkvariance / $k2));
$quizstats->errorratio = 100 * sqrt(1 - ($quizstats->cic / 100));
$quizstats->standarderror = $quizstats->errorratio *
$quizstats->standarddeviation / 100;
}
}
$this->cache_stats(quiz_statistics_qubaids_condition($quizid, $currentgroup, $groupstudents, $useallattempts), $quizstats);
return array($s, $quizstats);
}
/**
* Load the cached statistics from the database.
*
* @param $qubaids qubaid_condition
* @return The statistics for overall attempt scores or false if not cached.
*/
protected function get_cached_quiz_stats($qubaids) {
global $DB;
$timemodified = time() - self::TIME_TO_CACHE_STATS;
return $DB->get_record_select('quiz_statistics', 'hashcode = ? AND timemodified > ?',
array($qubaids->get_hash_code(), $timemodified));
}
/**
* @param $qubaids qubaid_condition
* @param $quizstats object the quiz stats to cache
*/
protected function cache_stats($qubaids, $quizstats) {
global $DB;
$toinsert = clone($quizstats);
$toinsert->hashcode = $qubaids->get_hash_code();
$toinsert->timemodified = time();
// Fix up some dodgy data.
if (isset($toinsert->errorratio) && is_nan($toinsert->errorratio)) {
$toinsert->errorratio = null;
}
if (isset($toinsert->standarderror) && is_nan($toinsert->standarderror)) {
$toinsert->standarderror = null;
}
// Store the data.
$DB->insert_record('quiz_statistics', $toinsert);
}
/**
* Get the quiz and question statistics, either by loading the cached results,
* or by recomputing them.
*
* @param object $quiz the quiz settings.
* @param int $currentgroup the current group. 0 for none.
* @param bool $nostudentsingroup true if there a no students.
* @param bool $useallattempts use all attempts, or just first attempts.
* @param array $groupstudents students in this group.
* @param array $questions question definitions.
@@ -791,45 +523,36 @@ class quiz_statistics_report extends quiz_default_report {
* - $subquestions The subquestions, if any, with an additional _stats field.
* - $s Number of attempts included in the stats.
*/
protected function get_quiz_and_questions_stats($quiz, $currentgroup,
$nostudentsingroup, $useallattempts, $groupstudents, $questions) {
protected function get_quiz_and_questions_stats($quiz, $currentgroup, $useallattempts, $groupstudents, $questions) {
$qubaids = quiz_statistics_qubaids_condition($quiz->id, $currentgroup, $groupstudents, $useallattempts);
$quizstats = $this->get_cached_quiz_stats($qubaids);
$qstats = new question_statistics($questions);
if (empty($quizstats)) {
$quizcalc = new quiz_statistics_calculator();
if ($quizcalc->get_last_calculated_time($qubaids) === false) {
// Recalculate now.
$qstats->calculate($qubaids);
if ($nostudentsingroup) {
list($s, $quizstats) = $this->get_empty_stats();
} else {
list($s, $quizstats) = $this->calculate_quiz_stats($quiz->id, $currentgroup, $useallattempts,
$groupstudents, count($questions), $qstats->get_sum_of_mark_variance());
}
$quizstats = $quizcalc->calculate($quiz->id, $currentgroup, $useallattempts,
$groupstudents, count($questions), $qstats->get_sum_of_mark_variance());
$questions = $qstats->questions;
$subquestions = $qstats->subquestions;
if ($s) {
if ($quizstats->s()) {
$this->calculate_responses_for_all_questions_and_subquestions($qubaids, $questions, $subquestions);
}
} else {
if ($useallattempts) {
$s = $quizstats->allattemptscount;
} else {
$s = $quizstats->firstattemptscount;
}
$quizstats = $quizcalc->get_cached($qubaids);
$qstats->get_cached($qubaids);
$questions = $qstats->questions;
$subquestions = $qstats->subquestions;
}
return array($quizstats, $questions, $subquestions, $s);
return array($quizstats, $questions, $subquestions);
}
protected function calculate_responses_for_all_questions_and_subquestions($qubaids, $questions, $subquestions) {
@@ -942,18 +665,6 @@ class quiz_statistics_report extends quiz_default_report {
$DB->delete_records('question_response_analysis', array('hashcode' => $qubaids->get_hash_code()));
}
/**
* @param bool $useallattempts whether we are using all attempts.
* @return the appropriate lang string to describe this option.
*/
protected function using_attempts_string($useallattempts) {
if ($useallattempts) {
return get_string('allattempts', 'quiz_statistics');
} else {
return get_string('firstattempts', 'quiz_statistics');
}
}
/**
* @param object $quiz the quiz.
* @return array of questions for this quiz.
mod/quiz/report/statistics/statistics_graph.php
+1 -2
View File
@@ -64,8 +64,7 @@ $qubaids = quiz_statistics_qubaids_condition($quizid, $currentgroup, $groupstude
// Load the rest of the required data.
$questions = quiz_report_get_significant_questions($quiz);
// Load enough data to check permissions.
$quizstatistics = $DB->get_record('quiz_statistics', array('hashcode' => $qubaids->get_hash_code()));
// Only load main question not sub questions.
$questionstatistics = $DB->get_records_select('question_statistics', 'hashcode = ? AND slot IS NOT NULL',
array($qubaids->get_hash_code()));
mod/quiz/report/statistics/tests/stats_from_steps_walkthrough_test.php
+2 -3
View File
@@ -45,8 +45,7 @@ class testable_quiz_statistics_report extends quiz_statistics_report {
$qubaids = quiz_statistics_qubaids_condition($quiz->id, $currentgroup, $groupstudents, $useallattempts);
$this->clear_cached_data($qubaids);
$questions = $this->load_and_initialise_questions_for_calculations($quiz);
return $this->get_quiz_and_questions_stats($quiz, $currentgroup, $nostudentsingroup,
$useallattempts, $groupstudents, $questions);
return $this->get_quiz_and_questions_stats($quiz, $currentgroup, $useallattempts, $groupstudents, $questions);
}
}
@@ -95,7 +94,7 @@ class quiz_report_statistics_from_steps extends mod_quiz_attempt_walkthrough_fro
$this->check_attempts_results($csvdata['results'], $attemptids);
$this->report = new testable_quiz_statistics_report();
list($quizstats, $questions, $subquestions, $s) = $this->report->get_stats($this->quiz);
list($quizstats, $questions, $subquestions) = $this->report->get_stats($this->quiz);
// These quiz stats and the question stats found in qstats00.csv were calculated independently in spreadsheet which is
// available in open document or excel format here :