The last two decades have seen an explosion of field experimentation in political science and economics. Field experiments are often seen as the gold standard for policy evaluation. If you want to know if an intervention will work, run a randomized controlled trial, and do it in a natural setting. Field experiments offer up a powerful mix of credible causal identification and real-world relevance. But there’s a catch: if you’ve seen one field experiment, you’ve seen one field experiment. A fi...