Multisite trials can clarify the average impact of a new program and the heterogeneity of impacts across sites. Unfortunately, in many applications, compliance with treatment assignment is imperfect. For these applications, we propose an instrumental variable (IV) model with person-specific and site-specific random coefficients. Site-specific IV…

This study tests the claim that word learning and retention in a second language are contingent upon a task's involvement load (i.e. the amount of need, search, and evaluation it imposes), as proposed by Laufer and Hulstijn (2001). Seventy-nine beginning learners of Spanish completed one of three vocabulary learning tasks that varied in the amount…