This post was initially written in French, in the Winter 2021. As Marilyn Strathern stated, Goodhart’s Law says that “when a measure becomes a goal, it ceases to be a good measure.” There are many economic applications, but this law also helps to understand the dangers of algorithmic decisions, or to explain the difficulty of using the data available since the beginning of the SARS-CoV-2 COVID-19 pandemic. Goodhart’s Law, public policy evaluation, and Facebook “When a measure becomes a goal, it ceases to be … <a href=“https://freakonometrics.hypotheses.org/6