Researchers attempting to show that music has positive effects on children need to understand and control for preexisting differences between those who do and do not select into musical participation in the first place. Within a large-scale, communitywide, prospective, longitudinal study of predominantly low-income, ethnically diverse students (N…

Evidence that teachers' short-term instructional effects persist over time and predict substantial long-run impacts on students' lives provides much of the impetus for a wide range of educational reforms focused on identifying and responding to differences in teachers' value-added to student learning. However, relatively little research has…