Evidence map›Paper›PMID 31517234›Full record

ArticleJournal of cognition2019

How Many Participants Do We Have to Include in Properly Powered Experiments? A Tutorial of Power Analysis with Reference Tables.

Marc Brysbaert

Registry-linked trialAbstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in Journal of cognition, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT07219914 (Akashic Records and Mental Health Outcomes), which is not on this map. Cited by 297 papers, 10 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
297citing papers in PubMed, 10 pooled it
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

NCT07219914 naactive not recruitingnot on this mapstarted 2024, after this paper: background citation

Akashic Records and Mental Health Outcomes

TypeinterventionalSponsorRasa Healing IncRan2024 to 2026Enrolled117ConditionsResilience, Connectedness, Depression, AnxietyArmsAkashic Records Session
3 · Its place in the literature

Who cites it

297 citing papers in PubMed, 10 syntheses or guidelines pooled it.

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  11. No evidence that same-language subtitles improve children's reading fluency.British journal of psychology (London, England : 1953) · 2026
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237 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

1 author.

Marc BrysbaertDepartment of Experimental Psychology, Ghent University, BE.ORCID 0000-0002-3645-3189

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Given that an effect size of d = .4 is a good first estimate of the smallest effect size of interest in psychological research, we already need over 50 participants for a simple comparison of two within-participants conditions if we want to run a study with 80% power. This is more than current practice. In addition, as soon as a between-groups variable or an interaction is involved, numbers of 100, 200, and even more participants are needed. As long as we do not accept these facts, we will keep on running underpowered studies with unclear results. Addressing the issue requires a change in the way research is evaluated by supervisors, examiners, reviewers, and editors. The present paper describes reference numbers needed for the designs most often used by psychologists, including single-variable between-groups and repeated-measures designs with two and three levels, two-factor designs involving two repeated-measures variables or one between-groups variable and one repeated-measures variable (split-plot design). The numbers are given for the traditional, frequentist analysis with p < .05 and Bayesian analysis with BF > 10. These numbers provide researchers with a standard to determine (and justify) the sample size of an upcoming study. The article also describes how researchers can improve the power of their study by including multiple observations per condition per participant.

Indexed as

Mathematical modelingStatistical analysisWorking memory

Identifiers

PMID31517234
PMCPMC6640316

What OpenQuestion holds

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Registered trials

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.