Campbell H, de Jong VMT, Debray TPA, Gustafson P
Hernán, using a hypothetical example, argues that policies that prevent researchers from conducting underpowered observational studies using existing databases are misguided explaining that "[w]hen a causal question is important, it is preferable to have multiple studies with imprecise estimates than having no study at all." While we do not disagree with the sentiment expressed, caution is warranted. Small observational studies are a major cause of distrust in science, mainly because their results are often selectively reported. The hypothetical example used to justify Hernán's position is too simplistic and overly optimistic. In this short response, we reconsider Hernán's hypothetical example and offer a list of other factors - beyond simply the importance of the question - that are relevant when deciding whether or not to pursue underpowered research.