R/p.cat.R

In vanLunteren/DescrTab: Creates a table with descriptive statistics

#' @title
#' p-value calculator for categorical variables
#'
#' @description
#' Calculate the p-value for categorial variables. The decision which test to use is equal to \code{\link{m.cat}}.
#' The p-value is calculated using one of the three tests: Wilcoxon-Test, McNemar-Test, Chi-Squared-Test.
#'
#' @usage
#' p.cat(x, group, paired = F, is.ordered = F, correct.cat = F, correct.wilcox = T, index = c(), create = "tex")
#'
#' @param x
#' Vector of the categorial variable.
#' @param group
#' Vector of the grouping variable.
#' @param paired
#' Logical. Is the categorial Variable paired?
#' @param is.ordered
#' Logical. Is the categorial Variable ordered?
#' @param correct.cat
#' Logical. Should correction be used in chi-sqared tests (see \code{\link{chisq.test}})
#' @param correct.wilcox
#' Logical. Should correction be used in wilcoxon tests (see \code{\link{wilcox.test}})
#' @param index
#' Optional. Label for the footnote.
#' The footnotes aren't produced in this function.
#' @param create
#' Which output document should be produced in the following step (one of "pdf", "tex", "knitr", or "word").
#' Only usefull if \code{index} is not \code{NULL}.
#'
#' @details
#' Wilcoxon-Test: A Test for a comparison of 2 (in)dependent, ordered samples. (see \code{\link{wilcox.test}}).
#' Kruskal_wallis-Test: A Test for a comparison of more than 2 (in)dependent, ordered samples. (see \code{\link{kruskal.test}}).
#' McNemar Test: A Test for a comparison of 2 or more than 2 dependent, not ordered samples. (see \code{\link{mcnemar.test}}).
#' Chi-Squared Test: A Test for a comparison of 2 or more than 2 independent, not ordered samples. (see \code{\link{chisq.test}}).
#'
#' @return
#' The p-value with index which test is ussed is returned.
#'
#' @author
#' Lorenz Uhlmann, Csilla van Lunteren
#'
#' @examples
#' \dontrun{
#' p.cat(x=rep(1:5,20), group=rep(1:4,25))
#' }
#'
p.cat <- function(x, group, paired = F, is.ordered = F, correct.cat = F, correct.wilcox = T, index = c(),
                  create = "tex") {
  if (is.ordered) {
    if (length(levels(group)) == 2) {
      pv <- wilcox.test(as.numeric(x) ~ group, paired = paired)$p.value
    } else {
      pv <- kruskal.test(x ~ group)$p.value
    }
  } else {
    if (paired) {
      pv <- mcnemar.test(table(x, group), correct = correct.cat)$p.value
    } else {
      pv <- chisq.test(x, group, correct = correct.cat)$p.value
    }
  }
  pv <- formatr(pv, 3, cl.z = T)
  if (!is.null(index)) {
    if (create == "word" | create == "R") {
      pv <- paste(pv, index, sep = "")
    } else {
      pv <- paste(pv, "$^", index, "$", sep = "")
    }
  }
  pv
}