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This manual is an R cheatsheet for Psychology students. It explains how to complete many tasks psychologists commonly do. Click through the table of contents to quickly find the task you need. Watch this video to learn how to install R and RStudio:

• Download R
• Download RStudio

Working with R Notebooks

How to install and load pacakges

Haven

Haven contains functions that lets R import SPSS, SAS, Stata, and other foreign files.

Documentation can be viewed here

# Check if haven is already installed and if it is, load it.
if (!require(haven)){
  # If it's not intalled, then tell R to install it.
  install.packages("haven", dependencies = TRUE)
  # Once it's installed, tell R to load it.
  library(haven)
}

summarytools

Summarytools provide useful functions for summarizing and visualizing data

Documentation can be viewed here

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

psych

Summarytools provide useful functions for summarizing and visualizing data

Documentation can be viewed here

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

Import Data

Use the read_sav() function from the Haven package to import an SPSS file into R.

Documentation can be viewed here

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

Scoring Variable

Extraversion

#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