Learn R: Create Composite Variable Assignment

Load Packages

haven

Import and export SPSS, STATA, and SAS files

if(!require(haven)){
  install.packages("haven", dependencies = TRUE)
  library(haven)
}

summarytools

Tools to quickly and neatly summarize data

if(!require(summarytools)){
  install.packages("summarytools", dependencies = TRUE)
  library(summarytools)
}

psych

Provides various procedures for psychological, psychometric, and personality research

if(!require(psych)){
  install.packages("psych", dependencies = TRUE)
  library(psych)
}

Import Data

dataset <- read_sav("https://osf.io/kd4ej/download")

Scoring Variable

#create dataframe with only relevant variables to work with
Extraversion <- data.frame (dataset$FFM_1, dataset$FFM_6, dataset$FFM_11, dataset$FFM_16, dataset$FFM_21, dataset$FFM_26, dataset$FFM_31, dataset$FFM_36)

#create list of 'keys'. The  numbers just refer to the order of the question in the data.frame() you just made. The most important thing is to mark the questions that should be reversed scored with a '-'. 
Extraversion.keys <- make.keys(Extraversion, list(Extraversion=c(1,-2,3,4,-5,6,-7,8)))

#score the scale
Extraversion.scales <- scoreItems (Extraversion.keys, Extraversion)

#save the scores
Extraversion.scores <- Extraversion.scales$scores
#save the scores back in 'dataset'
dataset$Extraversion <- Extraversion.scores[,]

#print the cronbach alpha
Extraversion.scales$alpha

      Extraversion
alpha    0.8141661