Science is Shaped by Wikipedia: Evidence From a Randomized Control Trial*

I sometimes think that general and popular treatises are almost as important for the progress of science as original work.” — Charles Darwin, 1865 As the largest encyclopedia in the world, it is not surprising that Wikipedia reflects the state of scientific knowledge. However, Wikipedia is also one of the most accessed websites in the world, including by scientists, which suggests that it also has the potential to shape science. This paper shows that it does. Incorporating ideas into a Wikipedia article leads to those ideas being used more in the scientific literature. This paper documents this in two ways: correlationally across thousands of articles in Wikipedia and causally through a randomized control trial where we add new scientific content to Wikipedia. We find that the causal impact is strong, with Wikipedia influencing roughly one in every three hundred words in related scientific journal articles. Our findings speak not only to the influence of Wikipedia, but more broadly to the influence of repositories of scientific knowledge. The results suggest that increased provision of information in accessible repositories is a cost-effective way to advance science. We also find that such gains are equity-improving, disproportionately benefitting those without traditional access to scientific information. JEL Codes: O31, O33, O32 *The authors would like to thank MIT for research funding and for the provision of a ridiculous amount of computing resources, Elsevier for access to full-text journal data, Dario Taraborelli at the Wikimedia Foundation for guidance, and Caroline Fry for excellent research assistance.