moodle/lang/en/help/exercise/comparisonofassessments.html

<p align="center"><b>Comparison of Assessments</b></p>

<p>In an exercise it is usual for a piece of work to be assessed twice. A 
    student assesses their work before submitting it and the teacher then 
    (re)assesses the work. The teacher's assessment uses the student's 
    assessment as the starting point. An exercise allows the teacher to award
    a proportion of the grade to the student's assessment, the remainder of 
    the grade is allocated to the teacher's assessment of the work. (The 
    maximum grades for these are called &quot;Grade for Student 
    Assessments&quot; and &quot;Grade for Submissions&quot; respectively.) Note
    that the grade from the student's assessment is not used. The student's 
    assessment is given a grade based on how well it matches the teacher's 
    assessment.</p>

<p>The degree of agreement between the student's and teacher's assessment is 
    based on the differences between the scores in individual elements 
    (actually the squared differences are used). The mean of these differences
    must to converted into a meaningful grade. The &quot;Comparison of 
    Assessments&quot; option allows the teacher a degree of control on how 
    these comparisons are converted into grades.</p>

<p>To get some idea on what effect this option has, take the (fairly simple) 
    case of an assessment which has ten Yes/No questions. For example the 
    assessment might use questions like "Is the chart correctly formatted?", 
    "Is the calculated profit $100.66?", etc. Assume there are ten such 
    questions. When the &quot;Very Lax&quot; setting is chosen, prefect 
    agreement between the student's and teacher's assessment gives a grade of
    100%, if there is only one question which does not match the grade is 90%, 
    two disagreements give a grade of 80%, three 
    disagreements 70%, etc.. That might seem very reasonable and you might be thinking 
    why is this option called a &quot;Very Lax&quot; comparison. Well, consider 
    the case of a student doing a completely random assessment where the 
    answers of the ten questions are simply 
    guessed. On average this would result in five of the ten questions being 
    matched. So the &quot;monkey's&quot; assessment would get a grade of around
    50%. The situation gets a little more sensible with the &quot;Lax&quot; 
    option, then 
    the random assessment gets around 20%. When the &quot;Fair&quot; option is 
    chosen, random guessing will result in a zero grade most of the 
    time. At this level, a grade of 50% is given when the two assessments agree 
    on eight questions of the ten. If three questions are in disagreement then 
    the grade given is 25%. When the option is set to &quot;Strict&quot; having 
    two questions out of sync gives a grade of 40%. Moving into the &quot;Very 
    Strict&quot; territory a disagreement in just two questions drops the grade to 
    35% and having a single question in disagreement gives a grade of 65%.</p>

<p>This example is sightly artifical as most assessments usually have elements 
    which have a range of values rather than just Yes or No. In those cases the 
    comparison is likely to result in somewhat higher grades then the values
    indicated above. The various levels (Very Lax, Lax, Fair...) are given so 
    that the teacher can fine tune the comparisons. If they feel that the grades
    being given for assessments are too low then this option should be moved 
    towards the &quot;Lax&quot; or even &quot;Very Lax&quot; choices. And 
    alternatively, if the grades for the student's assessments are, in general, 
    felt to be too high this option should be moved to either the 
    &quot;Strict&quot; or &quot;Very Strict&quot; choices. It is really a 
    matter of trial and error with the best starting point being the 
    &quot;Fair&quot; option.</p>

<p>During the course of the exercise the teacher may feel that the grades given
    to the student assessments are either too high or too low. These grades are
    shown on the exercise's Administration Page. In this case, the teacher can
    change the setting of this option and re-calculate the student assessment
    grades (the &quot;Grading Grades&quot;). The re-calculation is done by 
    clicking the &quot;Re-grade Student Assessments&quot; link found on the
    administration page of the exercise. This can be safely performed at any 
    time in the exercise.</p>