Statistical moderation is a process applied by the Victorian Curriculum and Assessment Authority (VCAA) to the scores awarded by teachers for school-based assessments. This process aligns schools’ assessments to the same standard, while maintaining the students’ rank order given by the school. The VCAA uses statistical moderation to ensure that school-based assessments given by different schools are comparable throughout Victoria. This supports school-based assessment results to be part of the Australian Tertiary Admission Rank (ATAR) calculation.
Fairness and equity for all
The VCE gives teachers some flexibility in deciding the teaching and learning activities, and the tasks they will use to assess the learning outcomes specified in each Study Design. As a result, the school-based assessments from two different schools will sometimes be constructed on two different assessment activities, although they will be assessing the same learning outcomes.
In a school where assessment tasks are easier and marking is generous, students would get higher marks for the same standard of work than they would in another school where the assessments and marking are harder. Statistical moderation aligns that difference in school-based assessments and marking scales. If we do not take account of this when using schools’ assessments to calculate the students’ study scores, some students would be treated unfairly.
Statistical moderation process
Statistical moderation compares and aligns the level and spread of each school's assessments of its students in a particular study against a common scale.
A step-by-step guide to moderating schools' assessments
Step 1: Identify the moderation group for each study at each school.
A moderation group is defined as all students enrolled in the selected study at a given school and its partner school.
For example, the moderation group for Legal Studies at a particular school is all the students doing Legal Studies at that school. If there are a number of Legal Studies classes at the school, the students in all the classes constitute the moderation group.
If a school has only a very small number of students doing a study, then it is best if the school forms small group partnerships with another school for moderation purposes. When this happens, students from both schools doing that study constitute the moderation group.
Some students have results that need special treatment. These results are initially left out of the moderation process, and the final scores for these students are calculated later, in line with the rest of the group. Results are removed for students who do not have:
- complete school-based assessments
- examination scores or GAT scores (in studies where the GAT scores are used in the moderation process)
- or who have an application for a Derived Examination Score.
Step 2: Form an external score for each student doing the study.
All students in a study sit the same external assessment, typically an examination. Examination scores therefore provide a common scale for measuring student achievement. In a small number of studies GAT and examination scores are used where a better match with schools’ assessments throughout the state is achieved. In all such cases, the examination scores will always be the major influence.
In studies with two examinations, scores from both examinations will be used.
The composite scale of examination scores and the GAT is known as the external score. The external score is used as the common scale for all schools teaching that study.
Statistical moderation puts all school-based assessment marks for the study onto this common scale so that they can be compared throughout the VCE system.
Step 3: The scales are aligned.
The scale of the external scores is aligned with the scale of the school-based assessment marks from each school. The alignment is done separately for each moderation group. The student's rank order, as determined by the school-based assessment mark, is preserved.
The scores are determined for both the school-based assessment scale and the external score scale: the highest achievement, the upper quartile, the median and the lower quartile. These scores are used as fixed points for aligning the two scales. In the alignment process the level of achievement of each student is unaltered.
Figure 1: Aligning the scales
- The highest* moderated score is aligned to the highest external score.
- The median* and quartiles* of the moderated scores are aligned to the median and quartiles of the external scores.
The moderation process aims to make the mean (average) of the moderated scores as close as possible to the mean of the external scores. Alignment is then applied to the school-based score for each student and each student is awarded with their final score.
The moderation process is not influenced by students with anomalously low external performances, or by students who did very poorly on the school-based assessment but very well on the external assessment.
* The highest, median and quartiles are scores at the top, middle, 25 per cent and 75 per cent positions in large moderation groups.
Key points to remember
- Statistical moderation is required so that school assessments can be used fairly as part of VCE assessment. It ensures that the assessment of all students, no matter what school they attend, is comparable and fair.
- Statistical moderation aligns schools’ assessments in accordance with students’ scores onto a common scale.
- Any adjustment to a student’s score is determined by the external scores for the whole group, not by the student’s own external score.
- Statistical moderation does not change the rank order of students as determined by the school’s school-based scores. A student given the top score for school-based assessments by his or her school will have the top score after statistical moderation, no matter how they perform on the exam(s).
- Students who have applied for a Derived Examination Score or have an unusual exam performance will not affect the moderation process.
- Students who do not complete their exams will still have their school-based scores statistically moderated, using information from the rest of the group.
Frequently asked questions from teachers
There are two very weak students in my class. Will they drag down the marks of the others?
No. Research has shown that this is not the case, provided that school-based assessments and marks are a valid reflection of their level of achievement. It would be a mistake to give them ‘encouragement marks’ just to make them appear to catch up with others in the class.
One student in my class performed very badly in the VCE exam. Will this drag down the marks of the others?
No. Analysis has shown that this does not happen. In a class of typical size there are some students who do a little better than expected and some who do a little worse; the effects on statistical moderation tend to cancel out. Students who perform significantly worse in the exam are omitted when the scales are aligned in statistical moderation.
Should low achievers be discouraged from sitting their VCE exam so that they do not drag down the results of other students?
There is no evidence that low achievers have this effect.
A student in my class was sick and did not take the GAT. Will this affect the results of the rest of the class?
No. This student’s results will not be used to align the scales.
Am I disadvantaging my top students if I cannot separate them at the top of the assessment scale?
This is quite possible. If these students have been getting 100 per cent regularly in school-based assessment scores they will tend to bunch at the top. These results will make ‘good’ students appear equal to ‘excellent’ students, denying the latter the opportunity to show how good they really are.
I am normally perceived as a 'hard' marker. Will this disadvantage my students?
All things being equal, a hard marker will award lower marks than a generous marker. However, your school’s marking scale will have no permanent effect on students because it is aligned by the common scale during statistical moderation. If there are two or more teachers of the same study at your school it is important that they are all equally hard markers.
Download our brochure (pdf - 1.76mb) on understanding statistical moderation in the VCE.
Partnership information can be found in the
VCE and VCAL Administrative Handbook Part B, Section 4.5.