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I'm really hoping someone here can help.

I have performed a chi-square test of independence, looking at men/women and early/late drop out from therapy. I have a p-value of 0.047. Do I need to do any post hoc testing on this? Men drop out almost 50:50 early:late whereas women drop out almost 25:75 early:late. Do I need post hoc testing for this and a Bonferroni correction, or is the answer simply:

The frequency of retention rates was compared across gender, finding a significant interaction (X2 (1) = 3.94, p = 0.047), indicating that females were more likely to be retained past the third CBT session than men.

Any help would be greatly appreciated.

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You are answering the research question by one single hypothesis test, so no need to think about multiple testing.

Your statement is okay. Maybe you could say something like:

x of xy (50%) men had an early drop out, while for female patients, the drop-out rate was y out of yz (25%). This difference is statistically significant at the 5% level (Chi-squared test-statistic ....., p value 0.047).

If the sample size is not too large, I actually would go for Fisher's exact test, especially since the result is close to non-significance.

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  • $\begingroup$ Hi Michael, Thank you for the quick response. That's really helpful! I hadn't considered Fisher's exact test could be used for this purpose! I will go and check this out now! Thanks again, it's really confusing because some texts on-line say things like for chi-square of more than 2 x 2 and sometimes even for 2 x 2 you might want to do post hoc testing. When would you need to do post hoc testing on a 2x2 - is that a thing? $\endgroup$
    – user261832
    Oct 6, 2019 at 18:27
  • $\begingroup$ Hi Michael, sorry, one more question, would I look at the fishers exact score for 2 sided or 1 sided? Thank you. $\endgroup$
    – user261832
    Oct 6, 2019 at 18:35
  • $\begingroup$ Just to be sure: You are in a 2x2 scenario, right? The Fisher's exact test would be two-sided (there, "sided" is meant regarding the odds ratio, which is 1 without association). $\endgroup$
    – Michael M
    Oct 6, 2019 at 19:02
  • $\begingroup$ Yeah, I think so! I have Gender = male/female and Dropout = early/late? $\endgroup$
    – user261832
    Oct 6, 2019 at 19:10
  • $\begingroup$ Sounds like 2x2! $\endgroup$
    – Michael M
    Oct 6, 2019 at 19:17

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