Rmisc/[tmp]convert.d.to.t.R

In wviechtb/escalc: Package for Computing Effect Sizes

#' @export
convert.d.to.t <- function(d, df=NULL, n1=NULL, n2=NULL, proportion=.5) {
  ### Obsolete; not basing computation on
  ### reversal of formula used in e.g.
  ### http://journal.frontiersin.org/article/10.3389/fpsyg.2013.00863/full
  #   return(ifelse(d < 0,
  #                 -1 * sqrt(sqrt(n) * abs(d)),
  #                 sqrt(sqrt(n) * abs(d))));
  
  if (is.null(df) && !is.null(n1) && !is.null(n2)) {
    groupSize1 <- n1;
    groupSize2 <- n2;
  }
  else if (!is.null(df) && is.null(n1) && is.null(n2)) {
    groupSize1 <-      proportion  * (df + 2);
    groupSize2 <- (1 - proportion) * (df + 2);
  }
  else {
    warning("Specify either df (and ideally proportion) or n1 and n2! Returning NA.");
    return(NA);
  }
  
  multiplier <- sqrt((1 / groupSize1) + (1 / groupSize2));
  
  t <- d / multiplier;
  
  return(t);
  
}