# Chi-squared planned contrasts comparison adjustment problem

I have Group A, B, C. My hypotheses are:

1) proportions of C are different from proportions of B (=independance)
2) proportions of A are NOT different from proportions of B (=NO independance)

results:

A: success = 0.085 n=50
B: Success = 0.167 n=50
C: Success = 0.380 n=50


If I do post-hoc contrasts using pairwise.prop.test() then I sacrifice power because there is no need to test C against A, especially given C against B is already significant.

The pairwise.prop.test() function provides p-value adjustment such as bonferroni, holm or BH, BY (see R documentation for p.adjust {stats} ).

1. Which of these adjustments is most appropriate if choosing to do all post-hoc comparisons?
2. Would it be OK to two conduct 2 Chi-squared tests and test B against C and A against B and double the p-values?

Thanks

• This is just a variation of your previous question at stats.stackexchange.com/questions/21061/…. Please combine them and indicate which one you would prefer to be closed. – whuber Jan 13 '12 at 21:34
• I deleted the other posts. Also this is different because I am asking about plannned comparisons, not posthoc comparisons. Also, I am asking about right adjustment question 2 is about an alternative... – user670186 Jan 14 '12 at 20:22