Hypothesis Tests and Edexcel

Recently I have been covering hypothesis tests with both my Year 12 and Year 13 further maths groups and I noticed differing wordings in exam mark schemes (Edexcel S2).

I’ve always taught that you cannot say “we accept \(H_0\)” as you can’t prove that \(H_0\) is correct, and that you should say something like “There is insufficient evidence to reject \(H_0\)“. However, as the example below from January 2013 shows they seem to be happy with you saying “accept \(H_0\)“:

January 2013

Screenshot 2016-03-12 20.02.02Screenshot 2016-03-12 20.02.20

But strangely they don’t always use this language:

May 2011

Screenshot 2016-03-12 19.48.14

Screenshot 2016-03-12 19.52.57

I’m interested – how do you teach it?

One reply on “Hypothesis Tests and Edexcel”

I would probably argue that “accept H_0” doesn’t imply that it is necessarily true, just that it is the thing you are accepting, and our broader knowledge as stasticians tells us that when someone makes a statistical claim then it is true only as far as a degree of significance. In the same way, saying “reject H_0” doesn’t mean it’s necessarily false. That said, when writing out my own solutions I am more likely to write something like “There is (in)sufficient evidence to accept/reject the manufacturer’s/instructor’s/researcher’s/trapeze artist’s claim” as a concluding statement.

The real shame is that Type I and Type II errors don’t appear until S4 (though of course you can discuss them earlier). I think they help students get a better idea that you are delivering a verdict with doubt built in.

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