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Contingency Tables

June 26, 2016

Our year 12s are back in school getting a good head start on their year 13 studies. One of my tutees asked why Contingency Tables (from the S2 course – goodness of fit test) were called that. I didn’t know but it seemed like a question worthy of exploring.

I asked twitter and got these responses:

@michiexile My guess would be because they give you quantified risks for systematic outcomes, to plan from.

@tslumley Pearson coined ‘contingency’ to mean ‘deviation from independence’ (with this link)

@MsGreenMaths  I don’t know, but always assumed it was because some values are contingent on others … ?

@BetterMaths i suppose as it’s a relationship between two or more categorical variables – they are ‘contingent’ on each other.

So, I now know that this was certainly a term created by Karl Pearson (or PMCC and other fame) in 1904. It appears that the name was chosen mainly because it’s a system for checking whether some entries in the table are contingent on others.

Let me know if you have more to add.

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