Understanding Mixed-Effects Models Through Data Simulation

• Published in: Advances in methods and practices in psychological science Vol. 4; no. 1
• Main Authors: DeBruine, Lisa M., Barr, Dale J.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.01.2021
• Subjects: open materials; lme4; R; power; mixed-effects models; simulation
• ISSN: 2515-2459; 2515-2467; 2515-2467
• DOI: 10.1177/2515245920965119

Experimental designs that sample both subjects and stimuli from a larger population need to account for random effects of both subjects and stimuli using mixed-effects models. However, much of this research is analyzed using analysis of variance on aggregated responses because researchers are not confident specifying and interpreting mixed-effects models. This Tutorial explains how to simulate data with random-effects structure and analyze the data using linear mixed-effects regression (with the lme4 R package), with a focus on interpreting the output in light of the simulated parameters. Data simulation not only can enhance understanding of how these models work, but also enables researchers to perform power calculations for complex designs. All materials associated with this article can be accessed at https://osf.io/3cz2e/.