"comorbidity" <- function(d1,d2,com,labels=NULL) { cl <- match.call() twobytwo <- matrix(c(com, d1-com,d2-com,1-d1-d2+com),ncol=2) if(is.null(labels)) { colnames(twobytwo) <- c("D1","d1") rownames(twobytwo) <- c("D2","d2")} else { colnames(twobytwo) <- c(labels[1],paste("-",labels[1],sep="")) rownames(twobytwo) <- c(labels[2],paste("-",labels[2],sep=""))} phi <- phi(twobytwo) Yule <- Yule(twobytwo) tetra<- tetrachoric(twobytwo) answer <- list(twobytwo=twobytwo,phi=phi,Yule=Yule,tetra=tetra,Call=cl) class(answer) <- c("psych","comorbid") return(answer) }