I have always learned that if you have a contingency table that violates the chi square assumption of more than 20% of cells having expected count less than 5, the chisq. test is invalid. If that happens use the fisher exact test. SAS is the only program that I have found to support the test greater than a 2x2 table. Does everyone agree with me to this point? Secondly, if there is a singificant result in the chi sq test, different procedures including simple nonparametric tests, marascuilo procedure or checking the residuals can serve as the post hoc test to see which subgroup is signficantly different in terms of its distribution of the y responses. Is there a "post hoc" test for the fisher's exact test. What is the next step if there is reported signficance for the fishers test. Let's assume this is nominal data since there is a whole slew of tests and models that can be run for nominal data.