It is a common practice for examinations to be 'marked on a curve'. There are clear advantages to such a practice, and I am sure the recent PSLE have been 'marked on a curve'.
One of the major advantages of marking on a curve, is that the average grades become pretty stable year after year, regardless of fluctuation in examination difficulty. It is common in such a system to see examination questions get more difficult and challenging as teachers introduce novel questions, often in responseto increasing ability of students to 'game' the examination.
Looking at the annual average scores will not reveal the changing difficulty level of the examination questions.
The average rates of passes for the PSLE for example remain flat through the years. This 'flatness' is boring..... but great for the MOE Annual Report.
The inherent problem here, one which is seldom recognized, is that such statistics play tricks on sub-group analysis. Let me explain....
You can see from the figure, that the Chinese students perform admirably, in fact above national averages. This is perhaps because they are best able to 'game' the PSLE exams. Because they do so well and are numerically the biggest contributor to the national average, their results essentially 'drive' the national average. And in fact determine the difficulty of the exam. As their performance improves, the pressure for the examination board (Singapore Examinations and Assessment Board) is to increase the difficulty of the exam. But you do not see this because the national average, being determined by a normalizing curve, remains identical year after year.
But what of the other sub-groups e.g. Malays and Indians? Their numbers being numerically smaller (much smaller) than the Chinese data are essentially numbers that are relative to the major sub-group, i.e. the Chinese data.
Therefore, an apparent decline in achievement of a non-Chinese sub-group, is not necessarily a decline in standards, but merely a decline in achievement relative to the Chinese sub-group. In reality, the absolute performance of all sub-groups may actually be improving. But these improvements are not visible, and tragically, not recognized.
One can speculate about why the Chinese sub-group does so well....but my guess is that they have better access to resources which help prepare them for exams and make them better at 'gaming' the examination.
By contrast, the GCE 'O' level examination is set by the University of Cambridge Local Examination Syndicate (UCLES) do not experience the same problem. This is because, the standards are determined by the UCLES and all our ethnic groups are relatively small components of the total numbers. Here you can see overall standards improving and the pass rates for the Malay students, often regarded as poor performers, possibly improving the most rapidly of the ethnic groups.
Why is this important?
Well..... I think it is extremely important for educators to recognize that there is a critical difference between telling students they are always doing worse every year no matter how hard they try, and encouraging them by recognizing that they are actually performing better every year, though perhaps not improving as rapidly as others. The former discourages and creates and sense of despondency and helplessness, while the latter is inherently affirming and encourages the community to do better.
6 years ago