diff --git a/mod/quiz/report/attemptsreport.php b/mod/quiz/report/attemptsreport.php
index fa4f0d46016..554bd91dca1 100644
--- a/mod/quiz/report/attemptsreport.php
+++ b/mod/quiz/report/attemptsreport.php
@@ -121,7 +121,7 @@ abstract class quiz_attempt_report extends quiz_default_report {
     protected function validate_common_options(&$attemptsmode, &$pagesize, $course, $currentgroup) {
         if ($currentgroup) {
             //default for when a group is selected
-            if ($attemptsmode === null  || $attemptsmode == QUIZ_REPORT_ATTEMPTS_ALL) {
+            if ($attemptsmode === null || $attemptsmode == QUIZ_REPORT_ATTEMPTS_ALL) {
                 $attemptsmode = QUIZ_REPORT_ATTEMPTS_STUDENTS_WITH;
             }
         } else if (!$currentgroup && $course->id == SITEID) {
@@ -137,94 +137,6 @@ abstract class quiz_attempt_report extends quiz_default_report {
         }
     }
 
-    /**
-     * Contruct all the parts of the main database query.
-     * @param object $quiz the quiz settings.
-     * @param string $qmsubselect SQL fragment from {@link quiz_report_qm_filter_select()}.
-     * @param bool $qmfilter whether to show all, or only the final grade attempt.
-     * @param int $attemptsmode which attempts to show.
-     *      One of the QUIZ_REPORT_ATTEMPTS_... constants.
-     * @param array $reportstudents list if userids of users to include in the report.
-     * @return array with 4 elements ($fields, $from, $where, $params) that can be used to
-     *      build the actual database query.
-     */
-    protected function base_sql($quiz, $qmsubselect, $qmfilter, $attemptsmode, $reportstudents) {
-        global $DB;
-
-        $fields = $DB->sql_concat('u.id', "'#'", 'COALESCE(quiza.attempt, 0)') . ' AS uniqueid,';
-
-        if ($qmsubselect) {
-            $fields .= "\n(CASE WHEN $qmsubselect THEN 1 ELSE 0 END) AS gradedattempt,";
-        }
-
-        $extrafields = get_extra_user_fields_sql($this->context, 'u', '',
-                array('id', 'idnumber', 'firstname', 'lastname', 'picture',
-                'imagealt', 'institution', 'department', 'email'));
-        $fields .= '
-                quiza.uniqueid AS usageid,
-                quiza.id AS attempt,
-                u.id AS userid,
-                u.idnumber,
-                u.firstname,
-                u.lastname,
-                u.picture,
-                u.imagealt,
-                u.institution,
-                u.department,
-                u.email' . $extrafields . ',
-                quiza.sumgrades,
-                quiza.timefinish,
-                quiza.timestart,
-                CASE WHEN quiza.timefinish = 0 THEN null
-                     WHEN quiza.timefinish > quiza.timestart THEN quiza.timefinish - quiza.timestart
-                     ELSE 0 END AS duration';
-            // To explain that last bit, in MySQL, qa.timestart and qa.timefinish
-            // are unsigned. Since MySQL 5.5.5, when they introduced strict mode,
-            // subtracting a larger unsigned int from a smaller one gave an error.
-            // Therefore, we avoid doing that. timefinish can be non-zero and less
-            // than timestart when you have two load-balanced servers with very
-            // badly synchronised clocks, and a student does a really quick attempt.';
-
-        // This part is the same for all cases - join users and quiz_attempts tables
-        $from = "\n{user} u";
-        $from .= "\nLEFT JOIN {quiz_attempts} quiza ON
-                                    quiza.userid = u.id AND quiza.quiz = :quizid";
-        $params = array('quizid' => $quiz->id);
-
-        if ($qmsubselect && $qmfilter) {
-            $from .= " AND $qmsubselect";
-        }
-        switch ($attemptsmode) {
-            case QUIZ_REPORT_ATTEMPTS_ALL:
-                // Show all attempts, including students who are no longer in the course
-                $where = 'quiza.id IS NOT NULL AND quiza.preview = 0';
-                break;
-            case QUIZ_REPORT_ATTEMPTS_STUDENTS_WITH:
-                // Show only students with attempts
-                list($usql, $uparams) = $DB->get_in_or_equal(
-                        $reportstudents, SQL_PARAMS_NAMED, 'u');
-                $params += $uparams;
-                $where = "u.id $usql AND quiza.preview = 0 AND quiza.id IS NOT NULL";
-                break;
-            case QUIZ_REPORT_ATTEMPTS_STUDENTS_WITH_NO:
-                // Show only students without attempts
-                list($usql, $uparams) = $DB->get_in_or_equal(
-                        $reportstudents, SQL_PARAMS_NAMED, 'u');
-                $params += $uparams;
-                $where = "u.id $usql AND quiza.id IS NULL";
-                break;
-            case QUIZ_REPORT_ATTEMPTS_ALL_STUDENTS:
-                // Show all students with or without attempts
-                list($usql, $uparams) = $DB->get_in_or_equal(
-                        $reportstudents, SQL_PARAMS_NAMED, 'u');
-                $params += $uparams;
-                $where = "u.id $usql AND (quiza.preview = 0 OR quiza.preview IS NULL)";
-                break;
-        }
-
-        return array($fields, $from, $where, $params);
-    }
-
     /**
      * Add all the user-related columns to the $columns and $headers arrays.
      * @param table_sql $table the table being constructed.
@@ -401,17 +313,22 @@ abstract class quiz_attempt_report_table extends table_sql {
     protected $quiz;
     protected $context;
     protected $qmsubselect;
+    protected $qmfilter;
+    protected $attemptsmode;
     protected $groupstudents;
     protected $students;
     protected $questions;
     protected $includecheckboxes;
 
-    public function __construct($uniqueid, $quiz, $context, $qmsubselect, $groupstudents,
-            $students, $questions, $includecheckboxes, $reporturl, $displayoptions) {
+    public function __construct($uniqueid, $quiz, $context, $qmsubselect, $qmfilter,
+            $attemptsmode, $groupstudents, $students, $questions, $includecheckboxes,
+            $reporturl, $displayoptions) {
         parent::__construct($uniqueid);
         $this->quiz = $quiz;
         $this->context = $context;
         $this->qmsubselect = $qmsubselect;
+        $this->qmfilter = $qmfilter;
+        $this->attemptsmode = $attemptsmode;
         $this->groupstudents = $groupstudents;
         $this->students = $students;
         $this->questions = $questions;
@@ -609,6 +526,89 @@ abstract class quiz_attempt_report_table extends table_sql {
         return '';
     }
 
+    /**
+     * Contruct all the parts of the main database query.
+     * @param array $reportstudents list if userids of users to include in the report.
+     * @return array with 4 elements ($fields, $from, $where, $params) that can be used to
+     *      build the actual database query.
+     */
+    public function base_sql($reportstudents) {
+        global $DB;
+
+        $fields = $DB->sql_concat('u.id', "'#'", 'COALESCE(quiza.attempt, 0)') . ' AS uniqueid,';
+
+        if ($this->qmsubselect) {
+            $fields .= "\n(CASE WHEN $this->qmsubselect THEN 1 ELSE 0 END) AS gradedattempt,";
+        }
+
+        $extrafields = get_extra_user_fields_sql($this->context, 'u', '',
+                array('id', 'idnumber', 'firstname', 'lastname', 'picture',
+                'imagealt', 'institution', 'department', 'email'));
+        $fields .= '
+                quiza.uniqueid AS usageid,
+                quiza.id AS attempt,
+                u.id AS userid,
+                u.idnumber,
+                u.firstname,
+                u.lastname,
+                u.picture,
+                u.imagealt,
+                u.institution,
+                u.department,
+                u.email' . $extrafields . ',
+                quiza.sumgrades,
+                quiza.timefinish,
+                quiza.timestart,
+                CASE WHEN quiza.timefinish = 0 THEN null
+                     WHEN quiza.timefinish > quiza.timestart THEN quiza.timefinish - quiza.timestart
+                     ELSE 0 END AS duration';
+            // To explain that last bit, in MySQL, qa.timestart and qa.timefinish
+            // are unsigned. Since MySQL 5.5.5, when they introduced strict mode,
+            // subtracting a larger unsigned int from a smaller one gave an error.
+            // Therefore, we avoid doing that. timefinish can be non-zero and less
+            // than timestart when you have two load-balanced servers with very
+            // badly synchronised clocks, and a student does a really quick attempt.';
+
+        // This part is the same for all cases - join users and quiz_attempts tables
+        $from = "\n{user} u";
+        $from .= "\nLEFT JOIN {quiz_attempts} quiza ON
+                                    quiza.userid = u.id AND quiza.quiz = :quizid";
+        $params = array('quizid' => $this->quiz->id);
+
+        if ($this->qmsubselect && $this->qmfilter) {
+            $from .= " AND $this->qmsubselect";
+        }
+        switch ($this->attemptsmode) {
+            case QUIZ_REPORT_ATTEMPTS_ALL:
+                // Show all attempts, including students who are no longer in the course
+                $where = 'quiza.id IS NOT NULL AND quiza.preview = 0';
+                break;
+            case QUIZ_REPORT_ATTEMPTS_STUDENTS_WITH:
+                // Show only students with attempts
+                list($usql, $uparams) = $DB->get_in_or_equal(
+                        $reportstudents, SQL_PARAMS_NAMED, 'u');
+                $params += $uparams;
+                $where = "u.id $usql AND quiza.preview = 0 AND quiza.id IS NOT NULL";
+                break;
+            case QUIZ_REPORT_ATTEMPTS_STUDENTS_WITH_NO:
+                // Show only students without attempts
+                list($usql, $uparams) = $DB->get_in_or_equal(
+                        $reportstudents, SQL_PARAMS_NAMED, 'u');
+                $params += $uparams;
+                $where = "u.id $usql AND quiza.id IS NULL";
+                break;
+            case QUIZ_REPORT_ATTEMPTS_ALL_STUDENTS:
+                // Show all students with or without attempts
+                list($usql, $uparams) = $DB->get_in_or_equal(
+                        $reportstudents, SQL_PARAMS_NAMED, 'u');
+                $params += $uparams;
+                $where = "u.id $usql AND (quiza.preview = 0 OR quiza.preview IS NULL)";
+                break;
+        }
+
+        return array($fields, $from, $where, $params);
+    }
+
     /**
      * Add the information about the latest state of the question with slot
      * $slot to the query.
diff --git a/mod/quiz/report/overview/overview_table.php b/mod/quiz/report/overview/overview_table.php
index 7efa3d8b79f..1da0ff7a8e4 100644
--- a/mod/quiz/report/overview/overview_table.php
+++ b/mod/quiz/report/overview/overview_table.php
@@ -37,86 +37,101 @@ class quiz_report_overview_table extends quiz_attempt_report_table {
 
     protected $regradedqs = array();
 
-    public function __construct($quiz, $context, $qmsubselect, $groupstudents,
-            $students, $detailedmarks, $questions, $includecheckboxes, $reporturl, $displayoptions) {
+    public function __construct($quiz, $context, $qmsubselect, $qmfilter,
+            $attemptsmode, $groupstudents, $students, $detailedmarks,
+            $questions, $includecheckboxes, $reporturl, $displayoptions) {
         parent::__construct('mod-quiz-report-overview-report', $quiz , $context,
-                $qmsubselect, $groupstudents, $students, $questions, $includecheckboxes,
-                $reporturl, $displayoptions);
+                $qmsubselect, $qmfilter, $attemptsmode, $groupstudents, $students,
+                $questions, $includecheckboxes, $reporturl, $displayoptions);
         $this->detailedmarks = $detailedmarks;
     }
 
     public function build_table() {
         global $DB;
 
-        if ($this->rawdata) {
-            $this->strtimeformat = str_replace(',', '', get_string('strftimedatetime'));
-            parent::build_table();
+        if (!$this->rawdata) {
+            return;
+        }
 
-            //end of adding data from attempts data to table / download
-            //now add averages at bottom of table :
-            $params = array($this->quiz->id);
-            $averagesql = '
-                    SELECT AVG(qg.grade) AS grade, COUNT(qg.grade) AS numaveraged
-                    FROM {quiz_grades} qg
-                    WHERE quiz = ?';
+        $this->strtimeformat = str_replace(',', '', get_string('strftimedatetime'));
+        parent::build_table();
 
-            $this->add_separator();
-            if ($this->is_downloading()) {
-                $namekey = 'lastname';
-            } else {
-                $namekey = 'fullname';
-            }
-            if ($this->groupstudents) {
-                list($usql, $uparams) = $DB->get_in_or_equal($this->groupstudents);
-                $record = $DB->get_record_sql($averagesql . ' AND qg.userid ' . $usql,
-                        array_merge($params, $uparams));
-                $groupaveragerow = array(
-                        $namekey => get_string('groupavg', 'grades'),
-                        'sumgrades' => $this->format_average($record),
-                        'feedbacktext'=> strip_tags(quiz_report_feedback_for_grade(
-                                            $record->grade, $this->quiz->id, $this->context)));
-                if ($this->detailedmarks && ($this->quiz->attempts == 1 || $this->qmsubselect)) {
-                    $avggradebyq = $this->load_average_question_grades($this->groupstudents);
-                    $groupaveragerow += $this->format_average_grade_for_questions($avggradebyq);
-                }
-                $this->add_data_keyed($groupaveragerow);
-            }
+        // End of adding the data from attempts. Now add averages at bottom.
+        $this->add_separator();
 
-            if ($this->students) {
-                list($usql, $uparams) = $DB->get_in_or_equal($this->students);
-                $record = $DB->get_record_sql($averagesql . ' AND qg.userid ' . $usql,
-                        array_merge($params, $uparams));
-                $overallaveragerow = array(
-                        $namekey => get_string('overallaverage', 'grades'),
-                        'sumgrades' => $this->format_average($record),
-                        'feedbacktext'=> strip_tags(quiz_report_feedback_for_grade(
-                                            $record->grade, $this->quiz->id, $this->context)));
-                if ($this->detailedmarks && ($this->quiz->attempts == 1 || $this->qmsubselect)) {
-                    $avggradebyq = $this->load_average_question_grades($this->students);
-                    $overallaveragerow += $this->format_average_grade_for_questions($avggradebyq);
-                }
-                $this->add_data_keyed($overallaveragerow);
-            }
+        if ($this->groupstudents) {
+            $this->add_average_row(get_string('groupavg', 'grades'), $this->groupstudents);
+        }
+
+        if ($this->students) {
+            $this->add_average_row(get_string('overallaverage', 'grades'), $this->students);
         }
     }
 
+    /**
+     * Add an average grade over the attempts of a set of users.
+     * @param string $label the title ot use for this row.
+     * @param array $users the users to average over.
+     */
+    protected function add_average_row($label, $users) {
+        global $DB;
+
+        list($fields, $from, $where, $params) = $this->base_sql($users);
+        $record = $DB->get_record_sql("
+                SELECT AVG(quiza.sumgrades) AS grade, COUNT(quiza.sumgrades) AS numaveraged
+                  FROM $from
+                 WHERE $where", $params);
+
+        if ($this->is_downloading()) {
+            $namekey = 'lastname';
+        } else {
+            $namekey = 'fullname';
+        }
+        $averagerow = array(
+            $namekey    => $label,
+            'sumgrades' => $this->format_average($record),
+            'feedbacktext'=> strip_tags(quiz_report_feedback_for_grade(
+                                        $record->grade, $this->quiz->id, $this->context))
+        );
+
+        if ($this->detailedmarks) {
+            $dm = new question_engine_data_mapper();
+            $qubaids = new qubaid_join($from, 'quiza.uniqueid', $where, $params);
+            $avggradebyq = $dm->load_average_marks($qubaids, array_keys($this->questions));
+
+            $averagerow += $this->format_average_grade_for_questions($avggradebyq);
+        }
+
+        $this->add_data_keyed($averagerow);
+    }
+
+    /**
+     * Helper userd by {@link add_average_row()}.
+     * @param array $gradeaverages the raw grades.
+     * @return array the (partial) row of data.
+     */
     protected function format_average_grade_for_questions($gradeaverages) {
         $row = array();
+
         if (!$gradeaverages) {
             $gradeaverages = array();
         }
+
         foreach ($this->questions as $question) {
             if (isset($gradeaverages[$question->slot]) && $question->maxmark > 0) {
                 $record = $gradeaverages[$question->slot];
                 $record->grade = quiz_rescale_grade(
                         $record->averagefraction * $question->maxmark, $this->quiz, false);
+
             } else {
                 $record = new stdClass();
                 $record->grade = null;
                 $record->numaveraged = null;
             }
+
             $row['qsgrade' . $question->slot] = $this->format_average($record, true);
         }
+
         return $row;
     }
 
@@ -276,30 +291,6 @@ class quiz_report_overview_table extends quiz_attempt_report_table {
         }
     }
 
-    /**
-     * Load the average grade for each question, averaged over particular users.
-     * @param array $userids the user ids to average over.
-     */
-    protected function load_average_question_grades($userids) {
-        global $DB;
-
-        $qmfilter = '';
-        if ($this->quiz->attempts != 1) {
-            $qmfilter = '(' . quiz_report_qm_filter_select($this->quiz, 'quiza') . ') AND ';
-        }
-
-        list($usql, $params) = $DB->get_in_or_equal($userids, SQL_PARAMS_NAMED, 'u');
-        $params['quizid'] = $this->quiz->id;
-        $qubaids = new qubaid_join(
-                '{quiz_attempts} quiza',
-                'quiza.uniqueid',
-                "quiza.userid $usql AND quiza.quiz = :quizid",
-                $params);
-
-        $dm = new question_engine_data_mapper();
-        return $dm->load_average_marks($qubaids, array_keys($this->questions));
-    }
-
     /**
      * Get all the questions in all the attempts being displayed that need regrading.
      * @return array A two dimensional array $questionusageid => $slot => $regradeinfo.
diff --git a/mod/quiz/report/overview/report.php b/mod/quiz/report/overview/report.php
index 42ef36983d9..c7e268149d4 100644
--- a/mod/quiz/report/overview/report.php
+++ b/mod/quiz/report/overview/report.php
@@ -129,8 +129,8 @@ class quiz_overview_report extends quiz_attempt_report {
         $questions = quiz_report_get_significant_questions($quiz);
 
         $table = new quiz_report_overview_table($quiz, $this->context, $qmsubselect,
-                $groupstudents, $students, $detailedmarks, $questions, $includecheckboxes,
-                $reporturl, $displayoptions);
+                $qmfilter, $attemptsmode, $groupstudents, $students, $detailedmarks,
+                $questions, $includecheckboxes, $reporturl, $displayoptions);
         $filename = quiz_report_download_filename(get_string('overviewfilename', 'quiz_overview'),
                 $courseshortname, $quiz->name);
         $table->is_downloading($download, $filename,
@@ -219,8 +219,7 @@ class quiz_overview_report extends quiz_attempt_report {
                     "END) AS gradedattempt, ";
             }
 
-            list($fields, $from, $where, $params) =
-                    $this->base_sql($quiz, $qmsubselect, $qmfilter, $attemptsmode, $allowed);
+            list($fields, $from, $where, $params) = $table->base_sql($allowed);
 
             $table->set_count_sql("SELECT COUNT(1) FROM $from WHERE $where", $params);
 
diff --git a/mod/quiz/report/responses/report.php b/mod/quiz/report/responses/report.php
index 8da9e642771..5282d3c7074 100644
--- a/mod/quiz/report/responses/report.php
+++ b/mod/quiz/report/responses/report.php
@@ -146,7 +146,8 @@ class quiz_responses_report extends quiz_attempt_report {
                 array('context' => $displaycoursecontext));
 
         $table = new quiz_report_responses_table($quiz, $this->context, $qmsubselect,
-                $groupstudents, $students, $questions, $includecheckboxes, $reporturl, $displayoptions);
+                $qmfilter, $attemptsmode, $groupstudents, $students, $questions,
+                $includecheckboxes, $reporturl, $displayoptions);
         $filename = quiz_report_download_filename(get_string('responsesfilename', 'quiz_responses'),
                 $courseshortname, $quiz->name);
         $table->is_downloading($download, $filename,
@@ -197,8 +198,7 @@ class quiz_responses_report extends quiz_attempt_report {
                 }
             }
 
-            list($fields, $from, $where, $params) =
-                    $this->base_sql($quiz, $qmsubselect, $qmfilter, $attemptsmode, $allowed);
+            list($fields, $from, $where, $params) = $table->base_sql($allowed);
 
             $table->set_count_sql("SELECT COUNT(1) FROM $from WHERE $where", $params);
 
diff --git a/mod/quiz/report/responses/responses_table.php b/mod/quiz/report/responses/responses_table.php
index cfb4633ddcf..cb2a48d4a8a 100644
--- a/mod/quiz/report/responses/responses_table.php
+++ b/mod/quiz/report/responses/responses_table.php
@@ -35,11 +35,12 @@ defined('MOODLE_INTERNAL') || die();
  */
 class quiz_report_responses_table extends quiz_attempt_report_table {
 
-    public function __construct($quiz, $context, $qmsubselect, $groupstudents,
-            $students, $questions, $includecheckboxes, $reporturl, $displayoptions) {
+    public function __construct($quiz, $context, $qmsubselect, $qmfilter,
+            $attemptsmode, $groupstudents, $students,
+            $questions, $includecheckboxes, $reporturl, $displayoptions) {
         parent::__construct('mod-quiz-report-responses-report', $quiz, $context,
-                $qmsubselect, $groupstudents, $students, $questions, $includecheckboxes,
-                $reporturl, $displayoptions);
+                $qmsubselect, $qmfilter, $attemptsmode, $groupstudents, $students,
+                $questions, $includecheckboxes, $reporturl, $displayoptions);
     }
 
     public function build_table() {