Installing R and the required packages

R

Install R from the Comprehensive R Archive Network (CRAN). Choose the binary distribution for your operating system.

Windows / macOS: download the installer from CRAN.
Linux: use your distribution’s package manager. On Debian / Ubuntu:
```
sudo apt install r-base r-base-dev
```

RStudio (recommended IDE)

RStudio Desktop is a free IDE that integrates R, Quarto, and a markdown editor. It is the recommended way to run the tutorials on this site.

Quarto

Install Quarto from quarto.org. The current version (1.4 or later) is required.

R packages

Install the R packages used by the tutorials with:

install.packages(c(
  "lme4",      # multilevel models
  "lmerTest",  # p-values and profile CIs for lme4
  "lavaan",    # structural equation modelling
  "dplyr",     # data manipulation
  "tibble",    # modern data frames
  "interactions",  # simple-slopes and interaction plots
  "semPlot",   # SEM path diagrams (used in some tutorials)
  "knitr",     # chunk engine for Quarto / R Markdown
  "rmarkdown"  # document rendering
), repos = "https://cloud.r-project.org")

The make deps target in the Makefile runs the same command.

Verifying the install

In a fresh R session, run:

library(lme4)
library(lmerTest)
library(lavaan)
library(dplyr)
library(interactions)

If all six lines return without error, your install is complete.

Troubleshooting

`lavaan` fails to load on Linux

lavaan depends on system-level BLAS / LAPACK libraries. On Debian / Ubuntu, install them with:

sudo apt install libblas-dev liblapack-dev

`interactions` cannot find `sim_slopes`

The sim_slopes function lives in the interactions package. If you have a typo or an older version, install the latest:

install.packages("interactions", repos = "https://cloud.r-project.org")

Quarto cannot find R

If quarto render fails with “cannot find R”, set the QUARTO_R environment variable to the path of your R binary:

# macOS / Linux
export QUARTO_R=/usr/local/bin/R

# Windows (PowerShell)
$env:QUARTO_R = "C:\Program Files\R\R-4.3.0\bin\R.exe"

R