Before revision:  To estimate the treatment effect, researchers usually regress their outcome on a treatment indicator and pair fixed effects, and cluster standard errors at the unit-of-randomization level , namely, at the village level in our example .
After revision:  To estimate the treatment effect, researchers often regress their outcome on a treatment indicator and pair fixed effects, and cluster standard errors at the unit-of-randomization level , namely, at the village level in our example .