Value-Added Scores

Value-added is a phrase that has become prominent in recent years. The term is associated with the effort to objectively measure teacher effectiveness. A classroom-level value-added score is a quantitative assessment of how much a teacher contributes to student learning in one academic year. It measures the change in the standardized test scores of students in a given class, or in multiple classes, taught by a given teacher. The scores are adjusted for differences in student characteristics and student scores on previous tests. The standard for academic growth in most states is the amount of academic growth students experience in a typical classroom.

Value-added scores at the top of the scale seem to be an indicator of powerful classroom dynamics. A large-scale study of the relationship between value-added scores and student outcomes examined the records of 1 million children who progressed from fourth grade to adulthood. The results were impressive. The students of HETs are more likely to attend college, earn higher salaries, live in better neighborhoods, and save more, and they are less likely to experience teenage pregnancy. The three economists who published the study were initially skeptical of value-added scores, but they concluded that “great teachers create great value.” In the paper the authors make some policy suggestions that have stirred great controversy, but the findings appear to remain valid.

Value-added scores are not without controversy. Standardized test scores do not always reliably measure student achievement, and a single measure cannot fully capture everything teachers contribute to student learning. Initially, we had our own reservations about the validity of value-added data, but our interactions with HETs convinced us that high value-added scores are associated with more than just an increase in test scores. We also contacted a number of principals and asked them to tell us about teachers in their building who consistently had high value-added scores. Almost every response was some variation of the statement He or she is one of the best teachers in my school.