Test Snell
In rsnell: Snell Scoring

knitr::opts_chunk$set(echo = TRUE)


setwd(dirname(rstudioapi::getActiveDocumentContext()$path))

library(dplyr)

source("../R/HelperFunctions.R")
source("../R/buildfreqtable.R")
source("../R/snell.R")

Create test data (from snell)

data <- data.frame(
 "X-3" = c(0,6,0,0,0,2,3,0,1,2,0,5),
 "X-2" = c(0,3,0,4,0,4,4,0,2,2,0,1),
 "X-1" = c(0,1,3,1,0,3,3,1,0,2,0,1),
 "X0" = c(3,0,2,2,0,1,0,1,0,0,0,0),
 "X1" = c(3,1,2,4,2,0,1,1,1,2,4,1),
 "X2" = c(2,1,4,0,5,2,1,5,4,4,1,3),
 "X3" = c(4,0,1,1,5,0,0,4,4,0,7,1),
 row.names = as.character(1:12)
)

str(data)

snell(data)

The originally published scores are: -1.1, 0.6, 1.6, 2.2, 2.8, 4.0, 5.8

The scores in the spreadsheet are: -1.1, 0.611887716, 1.602323384 ,2.186738697, 2.837534795, 4.012972486, 5.84348144

My results are slightly different from the published results for the outer two categories. I think mine are actually more accurate though since the deflection in the paper is based on a rule of thumb and mine is actually calculated.

Test Tong data

Create Test data from milton

tong <- data.frame(
  "Easy" = c(0,0,1,0,1),
  "Medium" = c(4,7,0,3,1),
  "Difficult" = c(25,44,20,28,15)
)
tong

snell(tong)

The published values in tong et al are: -1, 1.025, and 4.5

So rsnell produces very similar results, but not exactly the same. Unclear where the discrepancy comes from.

Demo buildfreqtable

mydata <- data.frame("Groups" = rep(c("A", "B", "C", "D"), 10),
                     "Scores" = round(runif(40, 0, 5)))
mydata

freqtable <- buildfreqtable(data = mydata, trait = "Scores", subgroup = "Groups")
freqtable

snell(freqtable)

Test binary failure

raw data

rawdata <- data.frame(Groups = rep(c("A", "B", "C", "D"), 10),
                      Scores = round(runif(40, 0, 1))
                      )

call buildfreqtable

#Runs with a warning
binaryfreqtable <- buildfreqtable(data = rawdata,
                                  trait = "Scores",
                                  subgroup = "Groups")
binaryfreqtable

snell(binaryfreqtable) #Snell will fail

Test that the order argument is working

mydata <- data.frame("Groups" = rep(c("A", "B", "C", "D"), 10),
                     "Scores" = sample(c("Easy", "Medium", "Hard"), 40, replace = T))
mydata

#should work
buildfreqtable(data = mydata,
               trait = "Scores",
               subgroup = "Groups",
               order = c("Easy", "Medium", "Hard"))


#should fail
buildfreqtable(data = mydata,
               trait = "Scores",
               subgroup = "Groups",
               order = c("x", "y", "z")) # wrong letters

# Will have wrong order due to alphabetical sorting. Warning will be raised
buildfreqtable(data = mydata,
               trait = "Scores",
               subgroup = "Groups")