What is chi-square? An example looking at Brexit

Chi-square has been described by the statistician Michael Crawley as something taught to geographers at school and misunderstood thereafter! It’s a mischievous comment and a shame if true because despite its off-putting calculations there is nothing particularly complicated about chi-square.

It’s just a way of asking if two ‘things’ are related to one another or not, and assessing the statistical evidence for it.

This tutorial:

• Shows how to fit a chi-square test to some data looking at the results of the referendum on leaving the EU

• Discusses how the chi-square test works - what it is actually doing and why

• Notes that the chi-square test is often not that useful and that there are often simpler approaches that can be better used instead

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This project was funded by the Nuffield Foundation, but the views expressed are those of the authors and not necessarily those of the Foundation