The confidence interval for a ratio can be estimated if the P value is reported.
Parameters:
(1) ratio (risk ratio, odds ratio, hazard ratio)
(2) reported P value
estimate =
= LN(ratio)
normal distribution test z =
= (-0.862) + SQRT(0.743 – (2.404 * LN(P value)))
standard error =
= ABS((estimate) / (z value))
low end 95% confidence interval on log scale = (estimate) – (1.96 * (standard error))
low end ratio =
= (EXP(low end on log scale)
high end 95% confidence interval log scale = (estimate) + (1.96 * (standard error))
high end ratio =
= (EXP(high end on log scale)
