To determine how well a particular medicine works, the least informative type of study is a lab study. Lab studies are reliable for discovering or measuring fundamental laws of nature like gravity, but their results are much less trustworthy when applied to complex biological or social systems like human bodies, earth’s ecosystem, or nations’ economies. That’s because they can’t accurately replicate all of the relevant variables and their interactions. The same is true of computer models, which are similar to lab studies in that they both use artificially controlled conditions. In the hierarchy of clinical evidence, randomized controlled trials are the “gold standard,” followed by observational studies, and then lab studies and models.