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  1. Moodle
  2. MDL-62769

"Statistics for question positions" graph shows last shown variant, not the stats for the overall question.

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: 3.2.9, 3.3.6, 3.4.3, 3.5
    • Fix Version/s: 3.4.5, 3.5.2
    • Component/s: Quiz
    • Testing Instructions:
      Hide
      1. Create a quiz
      2. Create a calculated question (https://docs.moodle.org/35/en/Calculated_question_type) and add two datasets.
      3. Using a few different student accounts, attempt the quiz. Any time you get dataset 1 get the question right. Any time you get the other dataset get it wrong.
      4. Now log in as teacher/admin, and go to Quiz -> Results -> Statistics.
      5. (This is not what is being tested, but you should see that one of the variants has facility index 100%, and the other 0%, and the overall facility index for this slot is somewhere inbetween.)
      6. Now look at the 'Statistics for question positions' graph. The facility index plotted should match the overall percentage from the table, not 0% or 100%.
      Show
      Create a quiz Create a calculated question ( https://docs.moodle.org/35/en/Calculated_question_type ) and add two datasets. Using a few different student accounts, attempt the quiz. Any time you get dataset 1 get the question right. Any time you get the other dataset get it wrong. Now log in as teacher/admin, and go to Quiz -> Results -> Statistics. (This is not what is being tested, but you should see that one of the variants has facility index 100%, and the other 0%, and the overall facility index for this slot is somewhere inbetween.) Now look at the 'Statistics for question positions' graph. The facility index plotted should match the overall percentage from the table, not 0% or 100%.
    • Affected Branches:
      MOODLE_32_STABLE, MOODLE_33_STABLE, MOODLE_34_STABLE, MOODLE_35_STABLE
    • Fixed Branches:
      MOODLE_34_STABLE, MOODLE_35_STABLE
    • Pull 3.5 Branch:
    • Pull Master Branch:

      Description

      This issue affects the statistics in quiz reporting when questions have variants.

      Some questions (e.g. qtype_stack) have random variants of the question.  When creating the statistics, the mod/quiz/report.php lists (A) overall stats for the question and then (B) stats for each individual variant.  At the bottom of the page is a graph.  However the graph shows the last listed variant, not the stats for the question.  This is a strange choice and is confusing. I think this is a bug.

      Example illustrating the bug.

      In the above example, the facility index of the question overall is 2/3, but the graph (purple bar) shows the facility index of 100%.  The random variant 2 has a facility index of 100%.  

      The graph shows the last displayed random variant, not the overall question.

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              Dates

              • Created:
                Updated:
                Resolved:
                Fix Release Date:
                10/Sep/18