Function to calculate the winning probability of an binary (control vs 1 variant) experiment. Reference: www.evanmiller.org/bayesian-ab-testing.html

ab_result.R

ab.result <- function(control_success, control_failed, variant_success, variant_failed){
  growth <- (variant_success/(variant_success+variant_failed))/(control_success/(control_success+control_failed))-1
  control_success <- control_success+1
  control_failed <- control_failed+1
  variant_success <- variant_success+1
  variant_failed <- variant_failed+1
  winning_prob <- 0
  for(i in 0:(variant_success-1)){
    winning_prob <- winning_prob + exp(lbeta(control_success+i, variant_failed+control_failed)
                         - log(variant_failed+i) - lbeta(1+i, variant_failed) - lbeta(control_success, control_failed))
  }
  return(list(winning_prob=winning_prob, growth=growth))
}