Warning message upon using chisq.test()

General
1

Hi,

I am getting a warning message when performing a Chi-square test.

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Can someone help explain why?

Best,
Charlie

2

I believe the warning is calling out the fact that you have fairly small cell sizes.

3

Okay, so nothing with how the test has been called, but more to be careful to trust the statistic?

4

Okay, so nothing with how the test has been called, but more to be careful to trust the statistic?

yes, exactly that

5

That is great, thank you.

6

You are effectively violating the rule of thumb regarding a chi squared test:

  • none of the classes should have an expected value of 0
  • not more then 20% of your classes should have <5

You have 18 different entry positions, but 6 of them (= 33%) have 5 or less as an entry. You should probably consider using an exact Fisher-Test in this case, to avoid violating the rule of thumb for chi squared tests (the computations are very expensive in this case, but your entries are rather small so it might be the better option here).

1 Like
7

Hi FactOREO,

Thank you very much for you comment. I will consider the Fisher-test instead.

8

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