This post is Part 2 on the topic of PSLE Aggregate and T-Scores. In the last post in this blog , How PSLE Aggregate and T-Scores are calculated, we saw how those scores are calcuated.

One concern parents and students have is that there may be bias towards language subjects because the total score is 200, while the total for Maths and Science is 100.

In this post, we will see that there is no bias towards any particular subject, although the total scores for languages is twice that of Maths and Science.

Below is a tabulation to show that T-score eliminates any bias that may occur due to more total marks allocated to a particular subject.

In the example above, the **Raw Score **of all subjects for this student is **90%**.**English** – 90% of 200 marks = **180 marks****MT** - 90% of 200 marks = **180 marks****Maths** – 90% of 100 marks = **90 mar**ks**Science** – 90% of 100 marks = **90 marks**

The **Average Score of the cohort** for all subjects is **50%** of the maximum score.**English** – 50% of 200 marks = **100 marks****MT** - 50% of 200 marks = **100 marks****Maths** – 50% of 100 marks = **50 marks****Science** – 50% of 100 marks = **50 marks****The Standard Deviation** (Std Dev) is **40% from the average**.**English** – 40% of 100 marks (the average) = **40 marks****MT** - 40% of 100 marks (the average) = **40 marks****Maths** – 40% of 50 marks (the average) = **20 marks****Science** – 40% of 50 marks (the average) = **20 marks**

Using the T-score formula 50 + 10(X-Y)/Z, we can note that for all the subjects, the T-Score is 70. Although English and MT have a total score of 200, while Maths and Science have a total score of 100, this is automatically adjusted with the T-Score calculation.**There is no bias towards any subject in the calculation of PSLE Aggregate and T-Scores**.

Parents and students need not be unduly worried.

This blog is managed by Song Hock Chye, author of Improve Your Thinking Skills in Maths (P1-P3 series), which is published and distributed by EPH.

## Saturday, November 24, 2007

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## 2 comments:

Thanks for the new info, but I still don't understand somethings:

1)For the cohort thing, is it the school's average or the whole Singapore's schools' average?

2)How do I estimate my aggregate when the teachers don't know the average?

Please reply to me quick because my PSLE is coming! Thanks!

1) It is the whole of Singapore's average.

2) From experience, your teachers will be able to tell roughly what is the average.

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