Before revision:  We revisit two strands of the empirical literature on persuasion to show that the persuasive effect is highly heterogeneous and studies based on binary instruments provide limited information about the average persuasion rate in a heterogeneous population.
After revision:  We revisit two strands of the empirical literature on persuasion to show that the persuasive effect is highly heterogeneous . We also show that the existence of a continuous instrument opens up the possibility of point identification for the policy-relevant population.