# Is a Chi Square Test of Independence on a 2×2 table redundant when I'm already reporting a 95% CI on the odds ratio?

I'm analyzing a 2×2 contingency table, and am required to a report a 95% CI on the Odds Ratio.

Is there any point in prefacing this with a Chi Square Test of Independence? I understand that if the Odds Ratio does not contain 1 then it is guaranteed that the Chi Square test would have been statistically significant, and if it does contain 1 it's guaranteed the Chi Square test would not have been statistically significant. Is the Chi Square Test providing any extra information of use, or is it totally redundant?

There are several ways of calculating a statistic from a two by two table which asymptotically follows the chi-squared distribution (Pearson, Yates, deviance, ...). There are also several ways of estimating a confidence interval for the odds ratio. Since they do not all agree whoever told you about the guarantee that a test and a ci would always agree should explain what s/he meant. Better to quote both and if necessary explain why they point to different conclusions.

You should do the 95% CI on the odds ratio. The equations can be found here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2938757/

Generally you do not do the Chi-square test because the cases are not independent of each other.