Proyectos de Subversion Moodle

<?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/>.

/**

 * Question behaviour type for deferred feedback with CBM behaviour.

 *

 * @package    qbehaviour_deferredcbm

 * @copyright  2012 The Open University

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

defined('MOODLE_INTERNAL') || die();

require_once(__DIR__ . '/../deferredfeedback/behaviourtype.php');

/**

 * Question behaviour type information for deferred feedback with CBM behaviour.

 *

 * @copyright  2012 The Open University

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class qbehaviour_deferredcbm_type extends qbehaviour_deferredfeedback_type {

    public function adjust_random_guess_score($fraction) {

        return question_cbm::adjust_fraction($fraction, question_cbm::default_certainty());

    }

    public function summarise_usage(question_usage_by_activity $quba, question_display_options $options) {

        global $OUTPUT;

        $summarydata = parent::summarise_usage($quba, $options);

        if ($options->marks < question_display_options::MARK_AND_MAX) {

            return $summarydata;

        }

        // Prepare accumulators to hold the data we are about to collect.

        $notansweredcount  = 0;

        $notansweredweight = 0;

        $attemptcount = array(

            question_cbm::HIGH => 0,

            question_cbm::MED  => 0,

            question_cbm::LOW  => 0,

        );

        $totalweight = array(

            question_cbm::HIGH => 0,

            question_cbm::MED  => 0,

            question_cbm::LOW  => 0,

        );

        $totalrawscore = array(

            question_cbm::HIGH => 0,

            question_cbm::MED  => 0,

            question_cbm::LOW  => 0,

        );

        $totalcbmscore = array(

            question_cbm::HIGH => 0,

            question_cbm::MED  => 0,

            question_cbm::LOW  => 0,

        );

        // Loop through the data, and add it to the accumulators.

        foreach ($quba->get_attempt_iterator() as $qa) {

            if (strpos($qa->get_behaviour_name(), 'cbm') === false || $qa->get_max_mark() < 0.0000005) {

                continue;

            }

            $gradedstep = $qa->get_last_step_with_behaviour_var('_rawfraction');

            if (!$gradedstep->has_behaviour_var('_rawfraction')) {

                $notansweredcount  += 1;

                $notansweredweight += $qa->get_max_mark();

                continue;

            }

            $certainty = $qa->get_last_behaviour_var('certainty');

            if (is_null($certainty) || $certainty == -1) {

                // Certainty -1 has never been used in standard Moodle, but is

                // used in Tony-Gardiner Medwin's patches to mean 'No idea' which

                // we intend to implement: MDL-42077. In the mean time, avoid

                // errors for people who have used TGM's patches.

                $certainty = question_cbm::default_certainty();

            }

            $attemptcount[$certainty]  += 1;

            $totalweight[$certainty]   += $qa->get_max_mark();

            $totalrawscore[$certainty] += $qa->get_max_mark() * $gradedstep->get_behaviour_var('_rawfraction');

            $totalcbmscore[$certainty] += $qa->get_mark();

        }

        // Hence compute some statistics.

        $totalquestions   = $notansweredcount + array_sum($attemptcount);

        $grandtotalweight = $notansweredweight + array_sum($totalweight);

        $accuracy         = array_sum($totalrawscore) / $grandtotalweight;

        $averagecbm       = array_sum($totalcbmscore) / $grandtotalweight;

        $cbmbonus         = $this->calculate_bonus($averagecbm, $accuracy);

        $accuracyandbonus = $accuracy + $cbmbonus;

        // Add a note to explain the max mark.

        $summarydata['qbehaviour_cbm_grade_explanation'] = array(

            'title' => '',

            'content' => html_writer::tag('i', get_string('cbmgradeexplanation', 'qbehaviour_deferredcbm')) .

                    $OUTPUT->help_icon('cbmgrades', 'qbehaviour_deferredcbm'),

        );

        // Now we can start generating some of the summary: overall values.

        $summarydata['qbehaviour_cbm_entire_quiz_heading'] = array(

            'title' => '',

            'content' => html_writer::tag('h3',

                    get_string('forentirequiz', 'qbehaviour_deferredcbm', $totalquestions),

                    array('class' => 'qbehaviour_deferredcbm_summary_heading')),

        );

        $summarydata['qbehaviour_cbm_entire_quiz_cbm_average'] = array(

            'title' => get_string('averagecbmmark', 'qbehaviour_deferredcbm'),

            'content' => format_float($averagecbm, $options->markdp),

        );

        $summarydata['qbehaviour_cbm_entire_quiz_accuracy'] = array(

            'title' => get_string('accuracy', 'qbehaviour_deferredcbm'),

            'content' => $this->format_probability($accuracy, 1),

        );

        $summarydata['qbehaviour_cbm_entire_quiz_cbm_bonus'] = array(

            'title' => get_string('cbmbonus', 'qbehaviour_deferredcbm'),

            'content' => $this->format_probability($cbmbonus, 1),

        );

        $summarydata['qbehaviour_cbm_entire_quiz_accuracy_and_bonus'] = array(

            'title' => get_string('accuracyandbonus', 'qbehaviour_deferredcbm'),

            'content' => $this->format_probability($accuracyandbonus, 1),

        );

        if ($notansweredcount && array_sum($attemptcount) > 0) {

            $totalquestions   = array_sum($attemptcount);

            $grandtotalweight = array_sum($totalweight);

            $accuracy         = array_sum($totalrawscore) / $grandtotalweight;

            $averagecbm       = array_sum($totalcbmscore) / $grandtotalweight;

            $cbmbonus         = $this->calculate_bonus($averagecbm, $accuracy);

            $accuracyandbonus = $accuracy + $cbmbonus;

            $summarydata['qbehaviour_cbm_answered_quiz_heading'] = array(

                'title' => '',

                'content' => html_writer::tag('h3',

                        get_string('foransweredquestions', 'qbehaviour_deferredcbm', $totalquestions),

                        array('class' => 'qbehaviour_deferredcbm_summary_heading')),

            );

            $summarydata['qbehaviour_cbm_answered_quiz_cbm_average'] = array(

                'title' => get_string('averagecbmmark', 'qbehaviour_deferredcbm'),

                'content' => format_float($averagecbm, $options->markdp),

            );

            $summarydata['qbehaviour_cbm_answered_quiz_accuracy'] = array(

                'title' => get_string('accuracy', 'qbehaviour_deferredcbm'),

                'content' => $this->format_probability($accuracy, 1),

            );

            $summarydata['qbehaviour_cbm_answered_quiz_cbm_bonus'] = array(

                'title' => get_string('cbmbonus', 'qbehaviour_deferredcbm'),

                'content' => $this->format_probability($cbmbonus, 1),

            );

            $summarydata['qbehaviour_cbm_answered_quiz_accuracy_and_bonus'] = array(

                'title' => get_string('accuracyandbonus', 'qbehaviour_deferredcbm'),

                'content' => $this->format_probability($accuracyandbonus, 1),

            );

        }

        // Now per-certainty level values.

        $summarydata['qbehaviour_cbm_judgement_heading'] = array(

            'title' => '',

            'content' => html_writer::tag('h3', get_string('breakdownbycertainty', 'qbehaviour_deferredcbm'),

                    array('class' => 'qbehaviour_deferredcbm_summary_heading')),

        );

        foreach ($attemptcount as $certainty => $count) {

            $key   = 'qbehaviour_cbm_judgement' . $certainty;

            $title = question_cbm::get_short_string($certainty);

            if ($count == 0) {

                $summarydata[$key] = array(

                    'title' => $title,

                    'content' => get_string('noquestions', 'qbehaviour_deferredcbm'),

                );

                continue;

            }

            $lowerlimit = question_cbm::optimal_probablility_low($certainty);

            $upperlimit = question_cbm::optimal_probablility_high($certainty);

            $fraction = $totalrawscore[$certainty] / $totalweight[$certainty];

            $a = new stdClass();

            $a->responses = $count;

            $a->idealrangelow  = $this->format_probability($lowerlimit);

            $a->idealrangehigh = $this->format_probability($upperlimit);

            $a->fraction       = html_writer::tag('span', $this->format_probability($fraction),

                    array('class' => 'qbehaviour_deferredcbm_actual_percentage'));

            if ($fraction < $lowerlimit - 0.0000005) {

                if ((pow($fraction - $lowerlimit, 2) * $count) > 0.5) { // Rough indicator of significance: t > 1.5 or 1.8.

                    $judgement = 'overconfident';

                } else {

                    $judgement = 'slightlyoverconfident';

                }

            } else if ($fraction > $upperlimit + 0.0000005) {

                if ((pow($fraction - $upperlimit, 2) * $count) > 0.5) {

                    $judgement = 'underconfident';

                } else {

                    $judgement = 'slightlyunderconfident';

                }

            } else {

                $judgement = 'judgementok';

            }

            $a->judgement = html_writer::tag('span', get_string($judgement, 'qbehaviour_deferredcbm'),

                    array('class' => 'qbehaviour_deferredcbm_' . $judgement));

            $summarydata[$key] = array(

                'title' => $title,

                'content' => get_string('judgementsummary', 'qbehaviour_deferredcbm', $a),

            );

        }

        return $summarydata;

    }

    protected function format_probability($probability, $dp = 0) {

        return format_float($probability * 100, $dp) . '%';

    }

    public function calculate_bonus($total, $accuracy) {

        $expectedforaccuracy = max(

            $accuracy * question_cbm::adjust_fraction(1, question_cbm::LOW) +

                (1 - $accuracy) * question_cbm::adjust_fraction(0, question_cbm::LOW),

            $accuracy * question_cbm::adjust_fraction(1, question_cbm::MED) +

                (1 - $accuracy) * question_cbm::adjust_fraction(0, question_cbm::MED),

            $accuracy * question_cbm::adjust_fraction(1, question_cbm::HIGH) +

                (1 - $accuracy) * question_cbm::adjust_fraction(0, question_cbm::HIGH)

        );

        // The constant 0.1 here is determinted empirically from looking at lots

        // for CBM quiz results. See www.ucl.ac.uk/~ucgbarg/tea/IUPS_2013a.pdf.

        // It approximately maximises the reliability of accuracy + bonus.

        return 0.1 * ($total - $expectedforaccuracy);

    }

}