What is publication bias, and how can researchers mitigate it?

• A. A bias that occurs when researchers selectively report significant results.
• B. The tendency to publish only studies with positive findings.
• C. A bias arising from editorial decisions against null findings.
• D. Publication bias favors positive findings; mitigate by preregistration, reporting all results, and publishing null results.

Answer: (D)

Publication bias is when the literature becomes distorted because studies with positive or significant results are more likely to be published than those with null or negative findings. This skews the overall picture researchers draw from the evidence.

The best answer describes both what the bias is and how to reduce it: the bias tends to favor positive findings, and researchers can mitigate it by preregistration (locking in hypotheses and analysis plans before collecting data), reporting all results (including non-significant ones), and publishing null results. Preregistration helps prevent flexible, post hoc decisions that inflate effects. Reporting all results ensures the full set of findings is available, reducing cherry-picking. Publishing null results adds informative data to the literature, countering the skew toward positive outcomes. Together, these practices promote a more accurate, reproducible evidence base.

Some options capture aspects of publication bias, like selective reporting or focusing on positive findings, but they don’t specify concrete ways to prevent the bias or a full picture of how to improve the literature. The combination of defining the bias and outlining practical mitigation makes the chosen answer the most complete.