R/diffMeans.R

In randomizationInference: Flexible Randomization-Based Inference

# pairwise difference of mean outcomes
# input: outcomes (y),
#        assignments (w),
#        calcOptions=list of options for calculating test statistic (if necessary),
# output: value of test statistic
# calcOptions$factor can denote the treatment factor to evaluate (1 is default)
# calcOptions$pair can denote the pair of treatment levels to compare (c(0, 1) is default)

diffMeans <- function(y, w, calcOptions = NULL) {
  # formatting
  if (sum(factor(w) == w) > 0) w <- data.matrix(w)
  if (ncol(w) == 1) w <- as.vector(w)
  # calculations
  if (is.null(calcOptions$pair)) calcOptions$pair <- c(0, 1)
  if (is.vector(w)) {
    mean(y[w == calcOptions$pair[2]]) - mean(y[w == calcOptions$pair[1]])
  } else {
    if (is.null(calcOptions$factor)) calcOptions$factor <- 1
    mean(y[w[, calcOptions$factor] == calcOptions$pair[2]]) - mean(y[w[, calcOptions$factor] == calcOptions$pair[1]])
  }
}