[jupiter90000]

Yes, you're right that chi-squared is non-parametric, my mistake. However, even non-parametric tests can have assumptions that should probably be checked into at least for a given data set. It may be robust to the violations the data collected may exhibit, I'm not sure. This article lists the assumptions for chi-squared test: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3900058/