#' Interaction 2x2 table #' #' Estimates the interactions from an 2x2 table under the #' null hypotheses of independence. #' #' @param x a 2x2 table #' @param margin if multidimensional table (larger than 2-dimensional), #' then the margin determines on which dimension the independene tables should be estimated. #' @param pTabMethod to estimate the propability table. Default is \sQuote{dirichlet}. Other available methods: #' \sQuote{classical} that is function \code{prop.table()} from package base or method \dQuote{half} that add 1/2 to each cell #' to avoid zero problems. #' @author Kamila Facevicova, Matthias Templ #' @return The independence table(s) with either relative or absolute frequencies. #' @references #' Facevicova, K., Hron, K., Todorov, V., Guo, D., Templ, M. (2014). #' Logratio approach to statistical analysis of 2x2 compositional tables. #' \emph{Journal of Applied Statistics}, 41 (5), 944--958. #' @export #' @examples #' data(employment) #' int2x2(employment) int2x2 <- function(x, margin=3, pTabMethod = c("dirichlet", "half", "classical")){ ## Matthias Templ, TU WIEN, 17.01.2013 based on Code from Kamila Facevicova from 16.1.2013 int2tab <- function(x){ if(!all.equal(dim(x), c(2,2))) stop("ind2.table is for 2x2 tables.") xint <- x xint[1,1] <- (x[1,1]*x[2,2])^(1/2) xint[2,1] <- (x[2,1]*x[1,2])^(1/2) xint[1,2] <- (x[2,1]*x[1,2])^(1/2) ## Kamila: is this true?? xint[2,2] <- (x[1,1]*x[2,2])^(1/2) pTab(xint, method="classical") } dn <- dimnames(x) if(length(dim(x)) == 2){ res <- int2tab(x) } else { res <- apply(x, margin, int2tab) res <- array(res, dim=c(2,2,ncol(res))) } dimnames(res) <- dn class(res) <- "int2x2" res }