In epidemiological studies it is often necessary to disentangle the pathways that link an exposure to an outcome. Typically the aim is to identify the total effect of the exposure on the outcome, the effect of the exposure that acts through a given set of mediators of interest (indirect effect) and the effect of the exposure unexplained by those same mediators (direct effect). The traditional a...

The communication of research findings is one of our most important functions. Not communicating research findings can be harmful in many ways. Publication bias is a well-known phenomenon that affects cancer epidemiology, biomarker research, and cancer prevention. As these areas grow, along with the technologies, the risk of publication bias grows. To avoid the pitfall of publication bias and e...

the field of cognitive psychology has increasingly provided scientific insights to explore how humans are subject to unconscious sources of evidentiary bias, leading to errors that can affect judgement and decision-making. increasingly these insights are being applied outside the realm of individual decision-making to the collective arena of policy-making as well. a recent editorial in this jou...

2012;379:1173. 26 Swanson JM. UK Biobank and selection bias. Lancet 2012; 380:110. 27 Davey Smith G, Lawlor DA, Harbord R et al. Clustered environments and randomized genes: a fundamental distinction between conventional and genetic epidemiology. PLoS Med 2007;4:e352. 28 Mayer-Schonberger V, Cukier K. Big Data. London: John Murray, 2013. 29 Mills H. Analytics: turning data into dollars. Forward...

Attenuation of the exposure-response relationship due to exposure measurement error is often encountered in epidemiology. Given that error cannot be totally eliminated, bias correction methods of analysis are needed. Many methods require more than one exposure measurement per person to be made, but the `group mean OLS method,' in which subjects are grouped into several a priori defined groups f...

Julian P T Higgins senior statistician , Douglas G Altman director , Peter C Gøtzsche director , Peter Jüni head of division , David Moher senior scientist 5 , Andrew D Oxman senior researcher , Jelena Savović postdoctoral fellow , Kenneth F Schulz vice president , Laura Weeks research associate , Jonathan A C Sterne professor of medical statistics and epidemiology , Cochrane Bias Methods Group...