Cited by 10,328Statistical Methods and Bayesian InferenceSyntax, Semantics, Linguistic VariationCategorization, perception, and language

Random effects structure for confirmatory hypothesis testing: Keep it maximal

Open access
Barr, Dale J., Levy, Roger, Scheepers, Christoph, Tily, Harry J.·2013·Journal of Memory and Language

Published version of a preprint

Abstract

Linear mixed-effects models (LMEMs) have become increasingly prominent in psycholinguistics and related areas. However, many researchers do not seem to appreciate how random effects structures affect the generalizability of an analysis. Here, we argue that researchers using LMEMs for confirmatory hypothesis testing should minimally adhere to the standards that have been in place for many decades. Through theoretical arguments and Monte Carlo simulation, we show that LMEMs generalize best when they include the maximal random effects structure justified by the design. The generalization performance of LMEMs including data-driven random effects structures strongly depends upon modeling criteria and sample size, yielding reasonable results on moderately-sized samples when conservative criteria are used, but with little or no power advantage over maximal models. Finally, random-intercepts-only LMEMs used on within-subjects and/or within-items data from populations where subjects and/or items vary in their sensitivity to experimental manipulations always generalize worse than separate F1 and F2 tests, and in many cases, even worse than F1 alone. Maximal LMEMs should be the 'gold standard' for confirmatory hypothesis testing in psycholinguistics and beyond.

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Integrity signals

Registry

Crossref · 10.1016/j.jml.2012.11.001

Cites

12 of 12 references verified0 citation errors · 0 not checkable

Statistics

Claims the paper makes

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • When the specified model failed to converge, the random effects structure was simplified following recommended procedures.

    “When the specified model failed to converge, we simplified the random effects structure following recommended procedures [7]: first removing correlation parameters among random effects, then if necessary removing random slopes for higher-order interactions, and only as a last resort removing random slopes for main effects of theoretical interest.”

    From All Public Voices Are Equal, But Are Some More Equal Than Others to LLMs? (2026) · cites this paper as [7]

    In “Coping with failures to converge” (page not available), the paper recommends considering removal of random correlations while retaining slopes for predictors of theoretical interest. It does not prescribe the cited sequence of removing higher-order interaction slopes before main-effect slopes, and it advises retaining critical slopes rather than treating their removal as a standard last resort. (LLM, conf=0.86)

    Experimental — accuracy not yet measured
  • Non-balanced design with non-independent observations is accounted for by fitting mixed effects models with random intercepts for strata, challenges, and individuals.

    “Essentially, we have a non-balanced design with non-independent observations and we account for it by fitting mixed effects models with random intercepts for strata, challenges, and individuals (Barr, Levy, Scheepers, & Tily, 2013).”

    From Relative Feedback Increases Disparities in Effort and Performance in Crowdsourcing Contests (2022) · cites this paper as Barr, Levy, Scheepers, & Tily, 2013

    In “Random effects in LMEMs and ANOVA,” the paper explains that random intercepts can account for clustering and non-independence across subjects and items. It does not prescribe intercepts for the citing study’s particular strata, challenges, and individuals. In “Identifying the maximal random effects structure,” it also advises trying random slopes for unbalanced within-unit designs, so intercepts alone are not generally sufficient. (LLM, conf=0.87)

    Experimental — accuracy not yet measured
  • The statistical model selection started with a maximal random effect structure imposed by the experimental design, and if it did not converge, random slopes and intercepts were iteratively reduced until convergence; if more than one model converged, the best-fit model was selected by AIC.

    “To identify the statistical model that would converge for each dependent variable, we started with a model that includes the dependent variable as a response variable with no fixed effects and a maximal random effect structure imposed by the experimental design (Barr et al., 2013). If the model did not reach convergence, we iteratively reduced the random effect structure by excluding random slopes”

    From The influence of landmark visualization style on task performance, visual attention, and spatial learning in a real-world navigation task (2024) · cites this paper as Barr et al., 2013

    Split into 2 atoms — 0 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 1 unverifiable. Expand the claim to see per-atom verdicts.

    Experimental — accuracy not yet measured
  • When non-Gaussian models with multiple random effects fail to converge, researchers often settle for a model that ignores non-independence and yields estimates with inappropriately high confidence and statistical significance.

    “which often lets researchers settle for a model that ignores non-independence and yields estimates with inappropriately high confidence and statistical significance (Arnqvist, 2020; Barr et al., 2013; Forstmeier et al., 2017)”

    From Violating the normality assumption may be the lesser of two evils (2021) · cites this paper as Barr et al., 2013

    In ‘Coping with failures to converge’ (page not provided), Barr et al. say maximal models often fail to converge, especially for categorical data, and warn against falling back to random-intercepts-only models. Their Results and Discussion say omitting relevant random effects can produce anticonservative tests. The paper does not establish how often researchers actually settle for such models, and it cautions that its results for continuous data may need modification for noncontinuous data. (LLM, conf=0.83)

    Experimental — accuracy not yet measured
  • A simulation that treats all workers as identical would fail to capture variation and might overestimate power.

    “A simulation which treated all workers as identical would fail to capture this variation, and hence might overestimate power (Barr et al., 2013).”

    From With Little Power Comes Great Responsibility (2020) · cites this paper as Barr et al., 2013

    The Method (Generating simulated data; page unavailable) includes variation among subjects in the simulations, and the Method (Performance metrics; page unavailable) warns that anticonservative analyses can have inflated apparent power. This supports the general concern about omitting individual variation, but the paper does not specifically test a simulation that treats workers as identical or show that it overestimates power. (LLM, conf=0.82)

    Experimental — accuracy not yet measured

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

The self-check needs the paper’s full text.

Cites

Flagged first, then by citations

Research works printed but not linked: 16

  1. Baayen RH Analyzing linguistic data: A practical introduction to statistics using R 2008 Cambridge Cambridge University Press
  2. Barr DJ Analyzing ‘visual world’ eyetracking data using multilevel logistic regression Journal of Memory and Language 2008 59 457 474
  3. Clark HH The language-as-fixed-effect fallacy: A critique of language statistics in psychological research Journal of Verbal Learning and Verbal Behavior 1973 12 335 359
  4. Forster K Dickinson R More on the language-as-fixed-effect fallacy: Monte carlo estimates of error rates for F1,F 2,F′, and min F′ Journal of Verbal Learning and Verbal Behavior 15 1976 135 142
  5. Gelman A Hill J Data Analysis Using Regression and Multilevel/Hierarchical Models 2007 Cambridge, MA Cambridge University Press
  6. Hadfield JD MCMC methods for multi-response generalized linear mixed models: The MCMCglmm R package Journal of Statistical Software 2010 33 1 22
  7. Kliegl R Toward a perceptual-span theory of distributed processing in reading: A reply to Rayner, Pollatsek, Drieghe, Slattery, and Reichle (2007) Journal of Experimental Psychology: General 2007 136 530 537 17696697
  8. Kuperman V Bertram R Baayen RH Processing trade-offs in the reading of Dutch derived words Journal of Memory and Language 2010 62 83 97
  9. Pinheiro JC Bates DM Mixed-Effects Models in S and S-PLUS 2000 New York Springer
  10. Plummer M JAGS: A program for analysis of Bayesian graphical models using Gibbs sampling Proceedings of the 3rd International Workshop on Distributed Statistical Computing 2003
  11. Raaijmakers JGW Schrijnemakers JMC Gremmen F How to deal with “ the Language-as-Fixed-effect fallacy”: Common misconceptions and alternative solutions Journal of Memory and Language 1999 41 416 426
  12. Roland D Relative clauses remodeled: The problem with mixed-effect models 2009 Poster presentation at the 2009 CUNY Sentence Processing Conference
  13. Santa JL Miller JJ Shaw ML Using Quasi F to prevent alpha inflation due to stimulus variation Psychological Bulletin 86 1979 37 46
  14. Scheffe H The analysis of variance 1959 New York Wiley
  15. Wickens TD Keppel G On the choice of design and of test statistic in the analysis of experiments with sampled materials Journal of Verbal Learning and Verbal Behavior 1983 22 296 309
  16. Winer BJ Statistical principles in experimental design 1971 2nd ed. New York McGraw-Hill

Cited by

Sorted by citations

Authors
Barr, D. J., Levy, R., Scheepers, C., & Tily, H. J.
Affiliations
  • University of Glasgow (GB)
  • Massachusetts Institute of Technology (US)
Corresponding author
Barr, Dale J.
Venue
Journal of Memory and Language
Publisher
Elsevier BV
Published
2013-04
Volume
68
Issue
3
Pages
255-278
ISSN
0749-596X (ISSN-L)
OpenAlex
W2141845152
Cited by
10,328
References
12
Citations by year
2026: 932 · 2025: 1029 · 2024: 937 · 2023: 928 · 2022: 991 · 2021: 1094 · 2020: 952 · 2019: 802 · 2018: 726 · 2017: 597 · 2016: 507 · 2015: 433 · 2014: 290 · 2013: 97 · 2012: 4
FWCI
360.53
Type
journal article
Language
en
Open access
Locations
  • Journal of Memory and Language (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
  • ENLIGHTEN (Jurnal Bimbingan dan Konseling Islam) (submittedVersion)
Funders
  • Economic and Social Research Council (ES/G045720/1)
  • Eunice Kennedy Shriver National Institute of Child Health and Human Development (R01HD065829)
Topics
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods and Bayesian Inference
  • Social Sciences › Arts and Humanities › Language and Linguistics › Syntax, Semantics, Linguistic Variation
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Categorization, perception, and language
Keywords
linear mixed models, generalizability, sample size, statistical power, within-subjects design, psycholinguistics

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review