lang/en_utf8/help/exercise/comparisonofassessments.html

   1 <h1>Comparison of Assessments</h1>
   2
   3 <p>In an exercise it is usual for a piece of work to be assessed twice. A
   4     student assesses their work before submitting it and the teacher then
   5     (re)assesses the work. The teacher's assessment uses the student's
   6     assessment as the starting point. An exercise allows the teacher to award
   7     a proportion of the grade to the student's assessment, the remainder of
   8     the grade is allocated to the teacher's assessment of the work. (The
   9     maximum grades for these are called &quot;Grade for Student
  10     Assessments&quot; and &quot;Grade for Submissions&quot; respectively.) Note
  11     that the grade from the student's assessment is not used. The student's
  12     assessment is given a grade based on how well it matches the teacher's
  13     assessment.</p>
  14
  15 <p>The degree of agreement between the student's and teacher's assessment is
  16     based on the differences between the scores in individual elements
  17     (actually the squared differences are used). The mean of these differences
  18     must be converted into a meaningful grade. The &quot;Comparison of
  19     Assessments&quot; option allows the teacher a degree of control on how
  20     these comparisons are converted into grades.</p>
  21
  22 <p>To get some idea on what effect this option has, take the (fairly simple)
  23     case of an assessment which has ten Yes/No questions. For example the
  24     assessment might use questions like "Is the chart correctly formatted?",
  25     "Is the calculated profit $100.66?", etc. Assume there are ten such
  26     questions. When the &quot;Very Lax&quot; setting is chosen, perfect
  27     agreement between the student's and teacher's assessment gives a grade of
  28     100%, if there is only one question which does not match the grade is 90%,
  29     two disagreements give a grade of 80%, three
  30     disagreements 70%, etc.. That might seem very reasonable and you might be thinking
  31     why is this option called a &quot;Very Lax&quot; comparison. Well, consider
  32     the case of a student doing a completely random assessment where the
  33     answers of the ten questions are simply
  34     guessed. On average this would result in five of the ten questions being
  35     matched. So the &quot;monkey's&quot; assessment would get a grade of around
  36     50%. The situation gets a little more sensible with the &quot;Lax&quot;
  37     option, then
  38     the random assessment gets around 20%. When the &quot;Fair&quot; option is
  39     chosen, random guessing will result in a zero grade most of the
  40     time. At this level, a grade of 50% is given when the two assessments agree
  41     on eight questions of the ten. If three questions are in disagreement then
  42     the grade given is 25%. When the option is set to &quot;Strict&quot; having
  43     two questions out of sync gives a grade of 40%. Moving into the &quot;Very
  44     Strict&quot; territory a disagreement in just two questions drops the grade to
  45     35% and having a single question in disagreement gives a grade of 65%.</p>
  46
  47 <p>This example is slightly artificial as most assessments usually have elements
  48     which have a range of values rather than just Yes or No. In those cases the
  49     comparison is likely to result in somewhat higher grades than the values
  50     indicated above. The various levels (Very Lax, Lax, Fair...) are given so
  51     that the teacher can fine tune the comparisons. If they feel that the grades
  52     being given for assessments are too low then this option should be moved
  53     towards the &quot;Lax&quot; or even &quot;Very Lax&quot; choices. And
  54     alternatively, if the grades for the student's assessments are, in general,
  55     felt to be too high this option should be moved to either the
  56     &quot;Strict&quot; or &quot;Very Strict&quot; choices. It is really a
  57     matter of trial and error with the best starting point being the
  58     &quot;Fair&quot; option.</p>
  59
  60 <p>During the course of the exercise the teacher may feel that the grades given
  61     to the student assessments are either too high or too low. These grades are
  62     shown on the exercise's Administration Page. In this case, the teacher can
  63     change the setting of this option and re-calculate the student assessment
  64     grades (the &quot;Grading Grades&quot;). The re-calculation is done by
  65     clicking the &quot;Re-grade Student Assessments&quot; link found on the
  66     administration page of the exercise. This can be safely performed at any
  67     time in the exercise.</p>
  68