Saturday, July 27, 2013

HSC and ATAR (5 of 10) - Moderation of Assessment Marks

Assessment Mark
For each HSC course Alex undertakes in Year 12, he completes the required assessment tasks as mandated by the school. Once the assessments are complete, the school submits the total assessment mark (called raw assessment mark) together with the rank order in his year group for each course to the Board of Studies (BOS):
                                                   Raw
Course                 Unit         assessment mark     Rank
Economics             2                  80/100              15
English Advanced   2                  90/100                1
Maths Ext. 1           2                 75/100                8
Maths Ext. 2           2                 85/100                4
Modern History       2                 72/100               38
History Ext.             1                 45/50                  2

As different schools may use different programs of  assessment tasks and have slightly different marking criteria, all school-submitted assessment marks are moderated by BOS in order to maintain fairness across schools. While the raw assessment marks might be influenced by individual schools, the HSC examination is used as a common scale to allow schools to be compared fairly as all students sit together in the open examination. The moderation process re-distributes the total raw examination marks of each HSC course obtained by the individual school during the HSC examination to all its students according to the students' performance in school (i.e. according to the ranking and their relative performance of each student in the school assessment). The process may sound complicated, but let's illustrate using Alex and his High School in one HSC course as an example.

Assuming Alex's class in Year 12 in his High School has 6 students (just hypothetical for simplicity), their raw assessment marks together with the rank order in the English Advanced course are submitted by the school. Their raw examination marks in the English Advanced course are also extracted from the HSC examination:
                         Raw                                      Raw
Course     assessment mark  Rank         examination mark  Rank
Alex                   90                1                        76               3
Ben                    78                2                        92               1
Charles               75                3                        80               2
Dylan                  58               4                         60               4
Edward              55                5                         50               6
Frank                 40                6                         51               5

Total                  396                                         409
Mean                  66                                           68

The moderation process works as follows:
1. the top raw assessment mark is adjusted to equal to the top raw examination mark (92).
2. the bottom raw assessment mark is adjusted to equal to the bottom raw examination mark (50)
3. the mean of the raw assessment marks of the school is adjusted to equal to the mean of the raw examination mark of the school (68)
4. basing on 1-3 and the statistics of all the raw examination marks of all the students in the school, a concave-up quadratic curve for the moderated assessment marks of all the students in the school is  established:

5. individual student's moderated assessment marks are then determined (can be read off) from the above quadratic curve from their raw assessment marks

As such, the moderated assessment marks for the English Advanced course of Alex's school are as follows:
                    Moderated
                assessment mark Rank
Alex                   92               1
Ben                    77               2
Charles               74              3
Dylan                  59              4
Edward               57              5
Frank                  50              6

Total                 409
Mean                 68

Note that:
1. the total moderated assessment mark of the school is equal to the total raw examination mark of the school (409), i.e. the total raw examination marks of the school is re-distributed as the moderated assessment marks of the school
2. the rank order of each student in the school assessment is maintained, i.e. Alex remains 1st and Ben remains 2nd, and so on in the raw assessment is the same as those in the moderated assessment
3. the relative performance between students is also maintained, i.e. the relative gaps between Alex/Ben, Ben/Charles etc in the raw assessment are the same as those in the moderated assessment.

The process is then repeated for all other courses Alex undertakes, and Alex's moderated assessment marks are calculated as follows:
                                      Moderated
Course                Unit  assessment mark
Economics             2          85/100
English Advanced   2          92/100
Maths Ext. 1           2          74/100
Maths Ext. 2           2          80/100
Modern History       2          70/100
History Ext.             1           44/50

After moderation, the school assessments (the assessment marks) are now on the same scale as the HSC examination (the examination marks), and are deemed fair across all schools. To cater for the difference in students' performance in different year, the moderated assessment marks are further aligned to the performance bands according to the current year's cut-offs similar to the alignment process of the raw examination marks. Alex's reported assessment marks are then calculated as follows:
                                          Reported
Course                Unit     assessment mark
Economics            2              92/100
English Advanced  2               96/100
Maths Ext. 1          2               80/100
Maths Ext. 2          2               88/100
Modern History      2               76/100
History Ext.            1                47/50

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