12.5.4.1 Computing NNT from a risk difference (RD)
12.5.4.2 Computing absolute risk reduction or NNT from a risk ratio (RR)
12.5.4.3 Computing absolute risk reduction or NNT from an odds ratio (OR)
12.5.4.4 Computing risk ratio from an odds ratio (OR)
12.5.4.5 Computing confidence limits