My question concerns how SPSS v22 does Bonferroni corrections for chisquare tests on contingency tables > 2x2 (nominal data). For example when doing the posthoc pairwise comparisons between the 4 groups (in columns), are the adjustments based on just the row or the whole matrix? For the former, the adjusted alpha level (threshold) would be 0.0083, (.05/6); for the latter it would seem to be .00167 (.05/30). Which are they using to declare that a pvalue is significant, while preserving the experimentwise alpha of 0.05? Their documentation is unclear on this issue.

You can find the adjustment formula in the Algorithms documentation under CROSSTABS. It is based on the subtable in the column proportions test. On Thu, Oct 13, 2016 at 8:39 AM, Emet Schneiderman <[hidden email]> wrote: My question concerns how SPSS v22 does Bonferroni corrections for chisquare 
<quote author="Jon Peck">
You can find the adjustment formula in the Algorithms documentation under CROSSTABS. It is based on the subtable in the column proportions test. Jon  Thanks for pointing me to the documentation. If I understand it correctly, the Bonferroni corrections are computed on a row by row basis, and do not account for the total number of rows in the contingency table (i.e., treated as independent). For example with a 6x4 contingency table (6 response levels in the rows and 4 groups in columns), there are 6 possible pairwise comparisons per row, so the adjusted alpha level (threshold) would be 0.00833, (.05/6). Is this your understanding? 
You can get the same result from the CTABLES column proportions test if you specify APAstyle significance indication. In the CTABLES output, you get a bit more explanation. Note: Values in the same row and subtable not sharing the same subscript are significantly different at p< .05 in the twosided test of equality for column proportions. Cells with no subscript are not included in the test. Tests assume equal variances. Tests are adjusted for all pairwise comparisons within a row of each innermost subtable using the Bonferroni correction. CTABLES now (V24) offers more choices and information. You can choose between Bonferroni and BenjaminiHockberg FDR, and you can get the actual significance levels if you choose a separate table for the results. You can also specify the significance levels you want and can get nonAPA style indicators, which I find more understandable. On Fri, Oct 14, 2016 at 10:41 AM, Emet Schneiderman <[hidden email]> wrote: You can find the adjustment formula in the Algorithms documentation under 
Free forum by Nabble  Edit this page 