Catalogue of bias: publication bias.

Dickersin and Min define publication bias as the failure to publish the results of a study ‘on the basis of the direction or strength of the study findings’.1 This non-publication introduces a bias which impacts the ability to accurately synthesise and describe the evidence in a given area.2 Publication bias is a type of reporting bias and closely related to dissemination bias, although dissemination bias generally applies to all forms of results dissemination, not simply journal publications. A variety of distinct biases are often grouped into the overall definition of publication bias.3 4