In published academic research, publication bias occurs when the outcome of an experiment or research study biases the decision to publish or otherwise distribute it. Publishing only results that show a significant finding disturbs the balance of findings in favor of positive results.[1] The study of publication bias is an important topic in metascience.
Despite similar quality of execution and design,[2] papers with statistically significant results are three times more likely to be published than those with null results.[3] This unduly motivates researchers to manipulate their practices to ensure statistically significant results, such as by data dredging.[4]
Many factors contribute to publication bias.[5][6] For instance, once a scientific finding is well established, it may become newsworthy to publish reliable papers that fail to reject the null hypothesis.[7] Most commonly, investigators simply decline to submit results, leading to non-response bias. Investigators may also assume they made a mistake, find that the null result fails to support a known finding, lose interest in the topic, or anticipate that others will be uninterested in the null results.[2] The nature of these issues and the resulting problems form the five diseases that threaten science: "significosis, an inordinate focus on statistically significant results; neophilia, an excessive appreciation for novelty; theorrhea, a mania for new theory; arigorium, a deficiency of rigor in theoretical and empirical work; and finally, disjunctivitis, a proclivity to produce many redundant, trivial, and incoherent works."[8]
Attempts to find unpublished studies often prove difficult or are unsatisfactory.[5] In an effort to combat this problem, some journals require studies submitted for publication pre-register (before data collection and analysis) with organizations like the Center for Open Science.
Other proposed strategies to detect and control for publication bias[5] include p-curve analysis[9] and disfavoring small and non-randomized studies due to high susceptibility to error and bias.[2]