Cited by 1,099Statistical Methods and Bayesian InferenceReliability and Agreement in MeasurementMental Health Research Topics

Lack of group-to-individual generalizability is a threat to human subjects research

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Fisher, Aaron J., Medaglia, John D., Jeronimus, Bertus F.·2018·Proceedings of the National Academy of Sciences

Abstract

Significance: The current study quantified the degree to which group data are able to describe individual participants. We utilized intensive repeated-measures data—data that have been collected many times, across many individuals—to compare the distributions of bivariate correlations calculated within subjects vs. those calculated between subjects. Because the vast majority of social and medical science research aggregates across subjects, we aimed to assess how closely such aggregations reflect their constituent individuals. We provide evidence that conclusions drawn from aggregated data may be worryingly imprecise. Specifically, the variance in individuals is up to four times larger than in groups. These data call for a focus on idiography and open science that may substantially alter best-practice guidelines in the medical and behavioral sciences.

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  • Between-person differences do not necessarily generalize to within-person changes.

    “Given that between-person differences do not necessarily generalize to within-person changes (Fisher et al., 2018), it is important to confirm previous between-person results regarding the structure of aversive reactivity and its associations with symptom change and extend these results to withinperson processes.”
  • SCEDs provide evidence of the effectiveness of interventions, drawing on substantially fewer participants than nomothetic approaches such as RCTs.

    “In doing this, SCEDs provide evidence of the effectiveness of interventions, drawing on substantially fewer participants than nomothetic approaches (such as RCTs) [51,52,53,54,55,56,57,58].”

    From Brief and Telehealth Acceptance and Commitment Therapy (ACT) Interventions for Stress in Inflammatory Bowel Disease (IBD): A Series of Single Case Experimental Design (SCED) Studies (2022) · cites this paper as [52]

    The Significance section discusses intensive within-person measurement and the limits of generalizing group findings to individuals. The Method and Discussion sections do not address whether single-case experimental designs establish intervention effectiveness with fewer participants than RCTs. Searches for single-case designs and comparative participant requirements found no supporting passage. (LLM, conf=0.75)

    Experimental — accuracy not yet measured
  • In clinical trials, individual outcomes within tested groups are aggregated but outcomes between individuals are rarely the same (e.g., the variance in individuals can be up to four times greater than in groups).

    “in clinical trials, individual outcomes within tested groups are aggregated but outcomes between individuals are rarely the same (e.g., the variance in individuals can be up to four times greater than in groups [12,13]).”
  • The inherent clinical heterogeneity associated with mental disorders may necessitate a greater focus on inter-individual differences to ensure generalisability to unseen cases.

    “However, it has been recognised that the inherent clinical heterogeneity associated with mental disorders may necessitate a greater focus on inter-individual differences to ensure generalisability to unseen cases (39, 43, 44).”

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2 of the 50 references couldn’t be matched to a known paper.

Research works printed but not linked: 1

  1. Wei WW (2006) Time series analysis. The Oxford Handbook of Quantitative Methods in Psychology (Oxford Univ Press, Oxford), Vol 2.

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Authors
Fisher, A. J., Medaglia, J. D., & Jeronimus, B. F.
Affiliations
  • University of California, Berkeley (US)
  • Drexel University (US)
  • University of Groningen (NL)
Corresponding author
Fisher, Aaron J.
Venue
Proceedings of the National Academy of Sciences
Published
2018-06-18
Volume
115
Issue
27
Pages
E6106-E6115
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
OpenAlex
W2808831456
Cited by
1,099
References
50
Citations by year
2026: 126 · 2025: 159 · 2024: 132 · 2023: 141 · 2022: 139 · 2021: 137 · 2020: 135 · 2019: 106 · 2018: 21 · 2017: 1 · 2013: 1
FWCI
82.78
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion, other-oa)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • eScholarship (California Digital Library) (submittedVersion)
  • University of Groningen research database (University of Groningen / Centre for Information Technology) (submittedVersion, other-oa)
Funders
HHS | NIH | National Institute of Mental Health (1-DP5- OD021352)
Topics
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods and Bayesian Inference
  • Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Reliability and Agreement in Measurement
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Mental Health Research Topics
Keywords
within-person variability, interindividual variability, aggregation bias, individual differences
MeSH terms
Anxiety Disorders, Bipolar Disorder, Female, Humans, Male, Psychotherapy, Group

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