At a time when teacher quality has emerged as a key factor in student learning, a statistical technique that determines the "value added" that teachers bring to student achievement is getting new scrutiny. Value-added measures compare students' growth in achievement to their expected growth, based on prior achievement and demographic…

Extensive education research on the contribution of teachers to student achievement produces two generally accepted results. First, teacher quality varies substantially as measured by the value added to student achievement or future academic attainment or earnings. Second, variables often used to determine entry into the profession and…