BMJ  2005;330:146 (15 January), doi:10.1136/bmj.330.7483.146-c

Letter

Issues in reporting epidemiological studies

Study raises several concerns

The first 150 words of the full text of this article appear below.

EDITOR—Pocock et al surveyed some recent epidemiological publications.¹ We agree with the general idea that the practice of reporting in epidemiologic publications needs improvement, but we are concerned about their methodological approach and conclusions.

Firstly, they say that few studies gave any power calculations to justify the study sizes. Ironically, Pocock et al's survey does not give any justification for the chosen study size of 73 epidemiological papers.

Secondly, Pocock et al's opinion on studies too small for meaningful analysis can be seen from a different point of view. Studies that are statistically underpowered are obviously less well planned and are often disregarded because they more often suffer from type I and type II errors compared with larger studies. However, from a public health perspective small studies may indicate true increased risks for exposures of interest that may have a substantial population-wide effect if the exposure is prevalent. . . . [Full text of this article]

Institute of Medical Informatics, Biometry and Epidemiology, University Hospital, University of Duisburg-Essen, Hufelandstrasse 55, D-45147 Essen, Gemany k-h.joeckel@uni-essen.de

Institute of Medical Epidemiology, Biometry and Informatics, Medical Faculty, Martin-Luther-University of Halle-Wittenberg, Magdeburger Strasse 27, D-06097 Halle, Germany andreas.stang@medizin.uni-halle.de

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