Evidence map›Paper›PMID 28884685›Full record

ArticleeLife2017

Standardized mean differences cause funnel plot distortion in publication bias assessments.

Peter-Paul Zwetsloot, Mira Van Der Naald, Emily S Sena, David W Howells, Joanna IntHout, Joris Ah De Groot, Steven Aj Chamuleau, Malcolm R MacLeod, Kimberley E Wever

Abstract read
PubMed Full text at PMC Publisher
In one paragraph

Article in eLife, 2017. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 101 papers, 66 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
101citing papers in PubMed, 66 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.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

101 citing papers in PubMed, 66 syntheses or guidelines pooled it.

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  12. Effects of resistance training on breast cancer-related arm lymphedema: a systematic review and dose-response meta-analysis.Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer · 2025
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41 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

9 authors.

Peter-Paul ZwetslootCardiology, Experimental Cardiology Laboratory, University Medical Center Utrecht, Utrecht, Netherlands.
Mira Van Der NaaldCardiology, Experimental Cardiology Laboratory, University Medical Center Utrecht, Utrecht, Netherlands.
Emily S SenaCenter for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.ORCID http://orcid.org/0000-0002-3282-8502
David W HowellsSchool of Medicine, University of Tasmania, Hobart, Australia.
Joanna IntHoutDepartment for Health Evidence, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, Netherlands.
Joris Ah De GrootJulius Center for Health Sciences and Primary care, University Medical Center Utrecht, Utrecht, Netherlands.
Steven Aj ChamuleauCardiology, Experimental Cardiology Laboratory, University Medical Center Utrecht, Utrecht, Netherlands.
Malcolm R MacLeodCenter for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom.ORCID http://orcid.org/0000-0001-9187-9839
Kimberley E WeverSystematic Review Centre for Laboratory Animal Experimentation (SYRCLE), Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, Netherlands.ORCID http://orcid.org/0000-0003-3635-3660

Funding

National Centre for the Replacement, Refinement and Reduction of Animals in Research NC/K000659/1National Centre for the Replacement, Refinement and Reduction of Animals in Research NC/L000970/1
6 · The paper itself

Abstract

Meta-analyses are increasingly used for synthesis of evidence from biomedical research, and often include an assessment of publication bias based on visual or analytical detection of asymmetry in funnel plots. We studied the influence of different normalisation approaches, sample size and intervention effects on funnel plot asymmetry, using empirical datasets and illustrative simulations. We found that funnel plots of the Standardized Mean Difference (SMD) plotted against the standard error (SE) are susceptible to distortion, leading to overestimation of the existence and extent of publication bias. Distortion was more severe when the primary studies had a small sample size and when an intervention effect was present. We show that using the Normalised Mean Difference measure as effect size (when possible), or plotting the SMD against a sample size-based precision estimate, are more reliable alternatives. We conclude that funnel plots using the SMD in combination with the SE are unsuitable for publication bias assessments and can lead to false-positive results.

Indexed as

Publication BiasStatistics as TopicMeta-Analysis as Topicdata simulationepidemiologyfunnel plotglobal healthhuman biologymedicinemeta-analysisnonepublication bias

Identifiers

PMID28884685
PMCPMC5621838

What OpenQuestion holds

Textmetadata
LicenceCC BY
Read underepoch 390

Registered trials

None linked

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.