Monday, 18 March 2013

League table lottery

It's not exactly news that school league tables have their problems, but I have rarely seen a better example of 'Lies, damned lies and statistics' at work than in the recently published secondary school league tables. Two observations I made - there was not a single school in Swindon in the comprehensives top 100, and my old school, Manchester Grammar School only came 65th in the independent schools.

Now the facts are that there are some very good comprehensives in Swindon, and that MGS is without doubt one of the top handful of independent schools in the country. So what went wrong?

In Dice World, my new book on randomness and probability, out next month, I point out that we are very good at reading meanings into numbers that just aren't there. In the case of these tables there is a totally bizarre assumption being made that the average number of points achieved at A level is somehow the same thing as relative merit of the school. But why would it be? I don't if it is still true but when I was at secondary school we were discouraged from doing too many A levels for the sake of it. It was considered more important to focus on the right things, to get the minimum required A levels for your course and the spend the rest of the time getting more rounded education. That's just one of many factors that could influence average A level scores adversely.

Should we have league tables like this at all? I'm not sure. But if we do, I am convinced that the measure used needs to be better thought through. For example it would be much more interesting to know how many university offers (perhaps graded by university, though that's another can of worms) were made to the students, rather than totalling up grades alone. That way you could include how well the school prepared them for interviews as well as crude exam passes.

There has to be a better way...

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