Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Experiment Videos

Grey literature in meta-analyses.

Vicki S Conn1, Jeffrey C Valentine, Harris M Cooper

  • 1Department of Psychological Sciences, University of Missouri-Columbia, USA. conn@missouri.edu

Nursing Research
|July 18, 2003
PubMed
Summary
This summary is machine-generated.

Related Concept Videos

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Assessment of Selective Reporting Biases in Studies Included in Campbell Systematic Reviews: A Systematic Review.

Campbell systematic reviews·2026
Same author

Solution to Improve State Health Outcomes and Access to Care for Medicare Beneficiaries: Full Practice of APRNs.

Journal of the American Medical Directors Association·2025
Same author

PROTOCOL: Assessment of outcome reporting bias in studies included in Campbell systematic reviews.

Campbell systematic reviews·2023
Same author

Introducing an online training course in Campbell systematic review methods.

Campbell systematic reviews·2023
Same author

Calling all nurses-Now is the time to take action on improving the quality of care in nursing homes.

Nursing outlook·2023
Same author

Can Non-Randomised Studies of Interventions Provide Unbiased Effect Estimates? A Systematic Review of Internal Replication Studies.

Evaluation review·2022

Including grey literature in meta-analyses is crucial. Excluding it leads to over-representation of significant findings and inflated effect size estimates, compromising overall research accuracy.

Area of Science:

  • Biostatistics
  • Research Methodology
  • Evidence Synthesis

Background:

  • Meta-analysis combines individual study results for cumulative conclusions.
  • Grey literature, including unpublished studies, is sometimes included but faces validity concerns.
  • Peer review status of grey literature raises questions about its data quality.

Purpose of the Study:

  • To evaluate the necessity of including grey literature in meta-analyses.
  • To explore strategies for managing grey literature in quantitative synthesis.
  • To assess if published studies represent broader research findings.

Main Methods:

  • Review of evidence on the representativeness of peer-reviewed studies versus broader research.
  • Examination of strategies for improving access to grey literature.

Related Experiment Videos

  • Analysis of methodological rigor in published versus grey literature.

    • Main Results:

    • Published research disproportionately reports statistically significant results compared to grey literature.
    • Effect size estimates in published studies are approximately one-third larger than in unpublished studies.
    • Methodological rigor is comparable between published and grey literature, with smaller or unfunded studies less likely to be published.

    Conclusions:

    • Excluding grey literature from meta-analyses overestimates statistically significant findings and inflates effect sizes.
    • Meta-analyses including grey literature provide more accurate and precise effect size estimates.
    • Inclusion of grey literature is recommended to fully represent the evidential base, with moderator analysis for methodological variations.