No Logbook, No Problem: Recovering LATE When You Can't Observe Compliance

Suppose you run a randomized experiment with imperfect compliance. You assigned treatment, measured outcomes, and now you want the LATE. The Wald estimator says divide the ITT by the compliance rate, $\pi = E[D_i \mid Z_i = 1] - E[D_i \mid Z_i = 0]$, and you&apos;re