rstats

This is a tutorial in progress on how to calculate Cronbach’s alphas using the psych package in R. library(tidyverse) library(psych) disgust <- read_csv("https://psyteachr.github.io/msc-data-skills/data/disgust.csv") SPSS Under the Analyze menu, choose Scale and Reliability Analysis.

I’m going to use intra-class correlations to demonstrate how to run an analysis on subgroups of data (because I’m constantly forgetting exactly how to do it). library(tidyverse) library(irr) Load the rating data for the open-source Face Research Lab London Set.

First, let’s make a data frame with two variables, a and b that are both sampled from a normal distribution with a mean of 0 and SD of 1. The variablle n will be how many samples we’ll take (100).

I often find myself needing to recode variables. I wrote previously about recoding a characters into a numbers using various coding schemes. But sometimes I want to recode numeric values into characters; this is particularly useful for graphing and for double-checking the meaning of your variable levels.

Download the Rmd notebook for this example Putting together this page made me realise I still don’t know anything about PCA and factor analysis. I use the psych package for SPSS-style PCA.

library(tidyverse) library(lmerTest) How you choose to code categorical variables changes how you can interpret the intercept and effects of those variables. My favourite tutorial on coding schemes explains things in detail.

You can use scale() to center and/or scale (i.e., Z-score) a vector of numbers. Z-score a list of numbers x <- c(10, 12, 14, 16, 18) scale(x) ## [,1] ## [1,] -1.

rep(x, times = 1, length.out = NA, each = 1) is pretty useful for simulating data. Here are some common recipes: Repeat a single number (1) a number of times (10) rep(1, 10) ## [1] 1 1 1 1 1 1 1 1 1 1 Repeat a series of numbers (1:5) a number of times (2) rep(1:5, 2) ## [1] 1 2 3 4 5 1 2 3 4 5 rep(1:5, times=2) ## [1] 1 2 3 4 5 1 2 3 4 5 If times is not an integer, it is truncated (not rounded).