title: [A new scientific source of bias: SILLY bias. Analysis of citations of BMJ's Christmas articles].
abstract: We analysed the scientific impact of systematic reviews and randomised trials published in the BMJ Christmas issues 1997-2006. The articles were mostly interpreted correctly as humorous, but the humorous dimension was overlooked with surprising ease. The result from one ironic-absurd trial on the effect of retroactive remote intercessory prayer for patients already dead or dismissed was taken at face value in 12/36 of the citing articles, and mortality data was unconditionally included in three systematic reviews. Thus, we document a new type of bias in medical research: Serious Idiopathic Loss of Ludic ironY (SILLY) bias, both in citation practices and in metaanalyses.
authors.affiliation: Det Nordiske Cochrane Center, Rigshospitalet, København Ø. ah@cochrane.dk
authors.forename: Ulrik A
authors.initials: UA
authors.lastname: Felding
authors.forename: Karsten J
authors.initials: KJ
authors.lastname: Jørgensen
authors.forename: Asbjørn
authors.initials: A
authors.lastname: Hróbjartsson
mesh_terms: D006801:Humans; D055811:Journal Impact Factor; D010506:Periodicals as Topic; D016032:Randomized Controlled Trials as Topic; D012196:Review Literature as Topic; D006113:United Kingdom; D014925:Wit and Humor as Topic