older/class_specific_material/SDS100/R/get_MAD_F_chisq_stat.R

In emeyers/ClassTools: Code useful for classes

# a function to get the MAD statistic
get_MAD_stat <- function(data, grouping) {


  group_means <- as.vector(by(data, grouping, mean))

  total <- 0
  num_differences <- 0

  for (iGroup1 in 1:(length(group_means) - 1)) {
    for (iGroup2 in (iGroup1 + 1):(length(group_means))) {

      total <- total + abs(group_means[iGroup1] - group_means[iGroup2])
      num_differences <- num_differences + 1

    }
  }


  total/num_differences


} # end of the function






# A function to get the F-statistic
get_F_stat <- function(data, grouping) {

  fit <- aov(data ~ grouping)
  fit_summary <- summary.aov(fit)
  fit_summary[[1]]$`F value`[1]

}


# A function to get the chi-squared statistic
get_chisqr_stat <- function(observed_counts, expected_proportions) {
  test_output <- chisq.test(observed_counts, p = expected_proportions)
  test_output$statistic
}