Statistically significant papers in psychiatry were cited more often than others
by other researchers are important in the dissemination of research
findings. We aimed to investigate whether preferential citation of
statistically significant articles exists in the psychiatric literature.
Study Design and SettingsWe
analyzed all original research papers published in 1996 in four
psychiatric journals. Using a standardized questionnaire, from each
paper, we extracted the primary outcome and its statistical
significance. The number of citations, excluding authors'
“self-citations,” received by April 2005 was obtained. Regression
analysis was used to relate citation frequency to statistical
significance, adjusting for confounders.
ResultsOf 448 extracted papers, 368 used statistical significance testing and 287 (77.8%) reported P<0.05.
The median number of citations for papers reporting “significant” and
“nonsignificant” results was 33 vs. 16. After adjustment for journal,
study design, reporting quality, whether outcome confirmed previous
findings and study size, the ratio of the number of citations per
article for articles reporting “P<0.05” on the primary outcome to those reporting “P>0.05” was 1.63 (95% confidence interval [CI]: 1.32, 2.02, P<0.001).
ConclusionAuthors cite studies based on their P-value
rather than intrinsic scientific merit. This practice skews the
research evidence. Systematic study registration and inclusion in
meta-analysis should be encouraged.
Statistically significant papers in psychiatry were cited more often than others - Journal of Clinical Epidemiology