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Using GAMMs to model trial-by-trial fluctuations in experimental data: More risks but hardly any benefit

Thul, R�diger; Conklin, Kathy; Barr, Dale J

Using GAMMs to model trial-by-trial fluctuations in experimental data: More risks but hardly any benefit Thumbnail


Authors

KATHY CONKLIN K.CONKLIN@NOTTINGHAM.AC.UK
Professor of Psycholinguistics

Dale J Barr



Abstract

Data from each subject in a repeated-measures experiment forms a time series , which may include trial-by-trial fluctuations arising from human factors such as practice or fatigue. Concerns about the statistical implications of such effects have increased the popularity of Generalized Additive Mixed Models (GAMMs), a powerful technique for modeling wiggly patterns. We question these statistical concerns and investigate the costs and benefits of using GAMMs relative to linear mixed-effects models (LMEMs). In a Monte Carlo simulation study, LMEMs that ignored time-varying effects were no more prone to false positives than GAMMs. Although GAMMs generally boosted power for within-subject effects, they reduced power for between-subject effects, sometimes to a severe degree. Our results signal the importance of proper subject-level randomization as the main defense against statistical artifacts due to by-trial fluctuations.

Citation

Thul, R., Conklin, K., & Barr, D. J. (2021). Using GAMMs to model trial-by-trial fluctuations in experimental data: More risks but hardly any benefit. Journal of Memory and Language, 120, Article 104247. https://doi.org/10.1016/j.jml.2021.104247

Journal Article Type Article
Acceptance Date Mar 31, 2021
Online Publication Date Apr 20, 2021
Publication Date Oct 1, 2021
Deposit Date Apr 14, 2021
Publicly Available Date Apr 21, 2022
Journal Journal of Memory and Language
Print ISSN 0749-596X
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 120
Article Number 104247
DOI https://doi.org/10.1016/j.jml.2021.104247
Public URL https://nottingham-repository.worktribe.com/output/5466193
Publisher URL https://www.sciencedirect.com/science/article/pii/S0749596X21000309

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