R/ce_accountanalysis.R

In NicolasJBM/manacc: Functions to simulate exercises in management accounting, and templates for these questions

#' Prepare figures for small exercises about the high-low method of cost estimation.
#' @param vol      Numeric. Volume of activity.
#' @param uvcs     Numeric vector. Unit Variable Costs for each account.
#' @param varprops Numeric vector. Percentage of each account which is variable.
#' @return A list with the base for the computation, the solution, the wrong_uvc and the wrong_fc for MCQ.
#' @export

ce_accountanalysis <- function(vol = 1000, uvcs = c(3,2), varprops = c(0.6,0.4)){
  
  volume <- NULL
  
  base <- data.frame(
    volume = vol,
    variable_costs = vol * uvcs,
    variable_prop = varprops
  )
  
  base$total_costs <- base$variable_costs / varprops
  base$fixed_costs <- base$total_costs - base$variable_costs
  base <- base[,c("volume", "variable_prop", "variable_costs", "fixed_costs", "total_costs")]
  base <- as.data.frame(apply(base, 2, round, digits = 2))
  
  solution <- list(
    volume = vol,
    variable = sum(base$variable_costs),
    fixed = sum(base$fixed_costs),
    uvc = sum(uvcs),
    fc = sum(base$fixed_costs)
  )
  
  prep_wrong <- base
  prep_wrong$wrong_vc1 <- prep_wrong$fixed_costs * prep_wrong$variable_prop
  prep_wrong$wrong_tc <- prep_wrong$fixed_costs / prep_wrong$variable_prop
  prep_wrong$wrong_tc <- prep_wrong$wrong_tc - prep_wrong$fixed_costs
  
  wrong_uvc <- c(
    wuvc1 = round(solution$fc / volume,2),
    wuvc2 = round(sum(base$total_costs) / volume,2),
    wuvc3 = round(sample(base$variable_costs,1) / volume,2),
    wuvc4 = round(sample(base$fixed_costs,1) / volume,2),
    wuvc5 = round(sum(prep_wrong$wrong_vc1) / volume,2),
    wuvc6 = round(sum(prep_wrong$wrong_vc2) / volume,2),
    wuvc7 = 0,
    wuvc8 = round(sample(c(0.75,0.8,0.85,0.9),1)*solution$uvc,2),
    wuvc9 = round(sample(c(1.1,1.15,1.2),1)*solution$uvc,2)
  )
  
  wrong_uvc <- unique(setdiff(wrong_uvc, solution$uvc))
  
  wrong_fc <- c(
    wfc1 = round(sum(prep_wrong$total_costs - vol * wrong_uvc[[1]]),2),
    wfc2 = round(sum(prep_wrong$total_costs - vol * wrong_uvc[[2]]),2),
    wfc3 = round(sum(prep_wrong$total_costs - vol * wrong_uvc[[3]]),2),
    wfc4 = round(sum(prep_wrong$total_costs - vol * wrong_uvc[[4]]),2),
    wfc5 = round(sum(base$variable_costs),2),
    wfc6 = round(sum(base$total_costs),2),
    wfc7 = 0,
    wfc8 = round(sample(c(0.75,0.8,0.85,0.9),1)*solution$fc,2),
    wfc9 = round(sample(c(1.1,1.15,1.2),1)*solution$fc,2)
  )
  
  wrong_fc <- unique(setdiff(wrong_fc, solution$fc))
  
  output <- list(
    base = base,
    solution = solution,
    wrong_uvc = wrong_uvc,
    wrong_fc = wrong_fc
  )
  
  return(output)
}