# Significant p-value and relative risk crossing 1

I am trying to convert results I am finding in scientific articles into relative risks so that I can compare studies in a meta analysis (if there is enough homogeneity in the studies).

I came across a study entitled "Intervention to improve practices of prescribing appropriate medication before an operation; pre-and-post-intervention study".

In the pre-intervention group, 16 out of 233 patients (so 217 with correct prescription) had an incorrect prescription and post intervention 3 out of 137 patients (134 with correct) had an incorrect prescription.

In the paper, a p-value of 0.046 was given, using Fisher's exact test. I checked it using a hand calculation and got 0.049. When I put this result into an RR calculator, I get a RR of 0.32 [0.09, 1.07]. Now I am a relative stats rookie but I thought the 95% CI should not cross 1 if my p-value for comparing two proportions is below 0.05.

• I think your p=0.049 was mistakenly taken from the chi-sq test. I used SPSS to check it, and the 2-side p value of Fisher's Exact test is 0.053; the p value of chi-sq is 0.049. That may explain why the 95% CI of RR crosses 1. – Penguin_Knight Aug 16 '12 at 11:28