I invited Kethmi Hettige to talk about the Z-score. For those who did A/Ls in Sri Lanka - this is a life deciding equation. Kethmi received her Bachelors in Industrial Statistics and Mathematical Finance from the Faculty of Science, University of Colombo. She is currently doing her PhD in Singapore.

00:00 About Z-score

00:59 Origins of the equation

01:52 Statistical measure

04:30 Mean,SD can be subjective

05:33 Why use it for A/Ls?

06:46 How to calculate it?

10:35 Problem with 2011 A/Ls

11:49 Bell curves

14:03 Biggest assumption with Z-score

16:09 Is it a good method?

20:22 Representative samples

21:35 What determines cutoff marks?