Scientific citations favor positive results: a systematic review and meta-analysis.

Bram Duyx, Miriam J E Urlings, Gerard M H Swaen, Lex M Bouter, Maurice P Zeegers

Journal: Journal of clinical epidemiology 2017;88():92-101

PMID: 28603008

Full Text on Elsevier Science View on PubMed

Abstract

OBJECTIVES

Citation bias concerns the selective citation of scientific articles based on their results. We brought together all available evidence on citation bias across scientific disciplines and quantified its impact.

STUDY DESIGN AND SETTING

An extensive search strategy was applied to the Web of Science Core Collection and Medline, yielding 52 studies in total. We classified these studies on scientific discipline, selection method, and other variables. We also performed random-effects meta-analyses to pool the effect of positive vs. negative results on subsequent citations. Finally, we checked for other determinants of citation as reported in the citation bias literature.

RESULTS

Evidence for the occurrence of citation bias was most prominent in the biomedical sciences and least in the natural sciences. Articles with statistically significant results were cited 1.6 (95% confidence interval [CI] 1.3-1.8) times more often than articles with nonsignificant results. Articles in which the authors explicitly conclude to have found support for their hypothesis were cited 2.7 (CI 2.0-3.7) times as often. Article results and journal impact factor were associated with citation more often than any other reported determinant.

CONCLUSION

Similar to what we already know on publication bias, also citation bias can lead to an overrepresentation of positive results and unfounded beliefs.

Address: CAPHRI School for Public Health and Primary Care, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands; NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands. Electronic address: [email protected].; CAPHRI School for Public Health and Primary Care, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands; NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands.; Department of Epidemiology and Biostatistics, VU University Medical Center, PO Box 7057, 1007 MB Amsterdam, The Netherlands; Department of Philosophy, Faculty of Humanities, Vrije Universiteit, De Boelelaan 1105, 1081 HV Amsterdam, The Netherlands.

DOI: 10.1016/j.jclinepi.2017.06.002

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MeSH Terms: Humans, Journal Impact Factor, Periodicals as Topic, Publication Bias