Cited by 241Meta-analysis and systematic reviewsStatistical Methods and Bayesian InferenceStatistical Methods in Epidemiology

Estimation of effect size under nonrandom sampling: the effects of censoring studies yielding statistically insignificant mean differences

Hedges, Larry V.·1984·Journal of Educational Statistics

Abstract

Quantitative research synthesis usually involves the combination of estimates of the standardized mean difference (effect size) derived from independent research studies. In some cases, effect size estimates are available only if the difference between experimental and control group means is statistically significant. If the quantitative result of a study is observed only when the mean difference is statistically significant, the observed mean difference, variance, and effect size are biased estimators of the corresponding population parameters. The exact distribution of the sample effect size is derived for the case in which only studies yielding statistically significant results may be observed. The maximum likelihood estimator of effect size also is derived under the model in which only significant results are observed. The exact distribution of the maximum likelihood estimator is obtained numerically and is used to study the bias of the maximum likelihood estimator. An empirical sampling study is used to supplement the analytic results.

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Crossref · 10.3102/10769986009001061

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  • Hedge's model assumes an extreme, or 'worst-case' form of bias.

    “Like the earliest fail-safe N methods, Hedge's model assumes an extreme, or 'worst-case' form of bias.”

    From A historical review of publication bias (2020) · cites this paper as Hedges, 1984

  • Hedges (1984) proposed the first model for study selection.

    “Hedges (1984) proposed the first model for study selection.”

    From A historical review of publication bias (2020) · cites this paper as Hedges, 1984

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Authors
Hedges, L. V.
Affiliations
University of Chicago (US)
Corresponding author
Hedges, Larry V.
Venue
Journal of Educational Statistics
Published
1984-03
Volume
9
Issue
1
Pages
61-85
ISSN
0362-9791 (ISSN-L)
OpenAlex
W2012120824
Cited by
241
References
27
Citations by year
2026: 11 · 2025: 13 · 2024: 14 · 2023: 13 · 2022: 13 · 2021: 15 · 2020: 18 · 2019: 21 · 2018: 17 · 2017: 12 · 2016: 9 · 2015: 5 · 2014: 5 · 2013: 4 · 2012: 2
FWCI
5.00
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Educational Statistics (publishedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
Funders
Spencer Foundation
Topics
  • Social Sciences › Decision Sciences › Statistics, Probability and Uncertainty › Meta-analysis and systematic reviews
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods and Bayesian Inference
  • Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
Keywords
effect size estimation, non-probability sampling, standardized mean difference, maximum likelihood estimator, estimation bias, exact distribution, meta-analysis, publication bias

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