Hello all, I am trying to calculate the effect size or power analysis for this study to assess my probability to detect a phenomenon/change, here are the details:

It is a case control study, matched for age and gender with a ratio 1:2 (N: 950/1900)
I want to test whether there is an association between a specific phenotype and a condition using the Chi square test at first (and then Bonferroni correction). There are four possible phenotypes so the contingency table should have 3df( condition matched to no condition on the column, phenotype, 4 types, on the row) and the prevalence of the certain phenotype is 25.4 for cases and 25.7 for controls (the phenotype should be protective). Summarizing:

test whether a certain phenotype is less likely associated to a certain condition
Chi square with Bonferroni correction
df 3
Cases 950 Controls 1900
prevalence of that phenotype is: Cases 25.4 Controls 25.7

I know that my numbers are relatively small and most likely not able to detect a small effect size but still interested to know how to proceed with this.

Thanks in advance!