MDL-17190 "error in code for calculating discrimination index and efficiency for...

diff --git a/mod/quiz/report/statistics/qstats.php b/mod/quiz/report/statistics/qstats.php
index 9a260d3673c0591d70a0e42f7c6eeb46ac1b3ac0..ef3509d105f27e8085016ff0d45ca73da58ddf5a 100644 (file)
--- a/mod/quiz/report/statistics/qstats.php
+++ b/mod/quiz/report/statistics/qstats.php
@@ -79,7 +79,11 @@ class qstats{
 
     function _secondary_states_walker($state, &$stats){
         $gradedifference = ($state->grade - $stats->gradeaverage);
-        $othergradedifference = (($state->sumgrades - $state->grade) - $stats->othergradeaverage);
+        if ($stats->subquestion){
+            $othergradedifference = $state->sumgrades - $stats->othergradeaverage;
+        } else {
+            $othergradedifference = (($state->sumgrades - $state->grade) - $stats->othergradeaverage);
+        }
         $overallgradedifference = $state->sumgrades - $this->sumgradesavg;
         $sortedgradedifference = (array_shift($stats->gradearray) - $stats->gradeaverage);
         $sortedothergradedifference = (array_shift($stats->othergradesarray) - $stats->othergradeaverage);