R/DiffPropStat.R

In Mediana: Clinical Trial Simulations

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# Compute the difference of proportions between two samples for binary variable based on non-missing values in the combined sample

DiffPropStat = function(sample.list, parameter) {

  # Determine the function call, either to generate the statistic or to return description
  call = (parameter[[1]] == "Description")

  if (call == FALSE | is.na(call)) {

    # Error checks
    if (length(sample.list)!=2)
      stop("Analysis model: Two samples must be specified in the DiffPropStat statistic.")

    # Merge the samples in the sample list
    sample1 = sample.list[[1]]

    # Merge the samples in the sample list
    sample2 = sample.list[[2]]

    # Select the outcome column and remove the missing values due to dropouts/incomplete observations
    outcome1 = sample1[, "outcome"]
    outcome2 = sample2[, "outcome"]
    prop1 = mean(stats::na.omit(outcome1))
    prop2 = mean(stats::na.omit(outcome2))
    result = (prop2 - prop1)
  }

  else if (call == TRUE) {
    result = list("Difference of proportions")
  }

  return(result)
}
# End of DiffPropStat