Wald confidence interval of risk ratio Note, the following code assumes the epitools library has been installed. For epitools help on this function, enter ?riskratio require(epitools) tabrisk=matrix(c(384,374,34,35),nc=2) riskratio(tabrisk, method="wald")

Gives something like this:

> riskratio(tabrisk, method="wald") $data Outcome Predictor Disease1 Disease2 Total Exposed1 384 34 418 Exposed2 374 35 409 Total 758 69 827 $measure risk ratio with 95% C.I. Predictor estimate lower upper Exposed1 1.000000 NA NA Exposed2 1.052064 0.6695936 1.653 $p.value two-sided Predictor midp.exact fisher.exact chi.square Exposed1 NA NA NA Exposed2 0.8269603 0.900074 0.8257292 $correction [1] FALSE attr(,"method") [1] "Unconditional MLE & normal approximation (Wald) CI"