LAUSR

testing. Consider the excellent article by Clayton et al. (“Women Grab Back: Exclusion, Policy Threat, and Women’s Political Ambition” forthcoming, American Political Science Review), who use focus groups with potential political candidates to generate a hypothesis that women’s political exclusion motivates their political ambition when combined with a policy threat to women’s interests. The paper thus uses theorization drawing from planned (and “exploratory”) observation of the world and especially from the perceptions and theories of political actors themselves. However, the authors also and subsequently pre-specify and conduct an experimental test (one which is also reproduced—meaningfully, I think—in two different samples). The combination of clearly inductive but also a priori theorization and subsequent pre-specification of an experimental test eases some concerns that might otherwise arise, for example, from an ex-post stipulation of an interactive hypothesis. From this example, one might draw the conclusion that—just as experiments are only one part of a long scientific process—so is pre-registration. Indeed, it might be possible to combine productively the best of both worlds. That is, we might integrate the slow work of designing excellent experiments with the somewhat faster work of, for instance, replication—even if as Druckman shows us the latter is often in fact properly thought of in terms of external validity and not “repetition.” Druckman’s masterful discussion shows how even seemingly uncontroversial aspects of the faster work are anything but straightforward. His emphasis thus invites us to focus on when and how experimental design can in fact inform empirical assessment of theories. This tremendous book offers lessons of experience earned by one of the foremost practitioners of the experimental craft. It deserves to be very widely read.