R/contab.R

In musto101/wilcox_R: What the package does (short line)

contab <-
function(dat,alpha=.05){
# dat is a 2by2 contingency table (matrix)
# Goal: compare the marginal probability of the first variable (e.g. Time 1)
# to the marginal probability of the second variable (e.g. Time 2).
# Issue: do the probabilities change from time 1 to time 2.
#
phat=dat
n=sum(phat)
phat=phat/n
p1.=phat[1,1]+phat[1,2]
p.1=phat[1,1]+phat[2,1]
del=p1.-p.1
sigsq=p1.*(1-p1.)+p.1*(1-p.1)-2*(phat[1,1]*phat[2,2]-phat[1,2]*phat[2,1])
sig=sqrt(sigsq/n)
test=abs(del)/sig
pv=2*(1-pnorm(test))
ci=del-qnorm(1-alpha/2)*sig
ci[2]=del+qnorm(1-alpha/2)*sig
list(delta=del,CI=ci,p.value=pv)
}