R/ORinv.R

In sasLM: 'SAS' Linear Model

ORinv = function(d0, conf.level=0.95)
{
  y1 = d0[, "y1"]
  n1 = d0[, "n1"]
  y2 = d0[, "y2"]
  n2 = d0[, "n2"]
  if (any(c(y1, n1 - y1, y2, n2 - y2) < 0) | any(n1*n2 == 0)) stop("Check the input!")

  r1 = OR(y1, n1, y2, n2, conf.level=conf.level)

  ai = y1
  bi = n1 - y1
  ci = y2
  di = n2 - y2
  ni = n1 + n2

  thi = log(r1$OR)
  vi = r1$SElog^2
  wi = 1/vi
  sumwi = sum(wi)
  pe = exp(sum(wi*thi)/sumwi)
  selog = sqrt(1/sumwi)

  z.crit = qnorm(0.5 + conf.level/2)
  lower = exp(log(pe) - z.crit*selog)
  upper = exp(log(pe) + z.crit*selog)
  r2 = data.frame(OR = pe, SElog = selog, lower = lower, upper = upper)
  return(list(ORs=r1, Common=r2))
}