Publication bias can result from the selective publication of manuscripts based on the direction and magnitude of results, multiple publication of results, and selective reporting of results within a published study. In particular, research with statistically significant positive results is more likely to be submitted for publication, to be published, and to be published more quickly than research with negative or nonsignificant results. Consequently, published studies on a particular topic might not be representative of all valid studies conducted on the topic, leading to distortion of the scientific record.

Publication bias tends to be greater in clinical research than in public health research, and in observational studies as opposed to randomized studies. Nevertheless, it has been demonstrated across all these types of research. One area where ...