How to Improve the Supply of High-Quality Teachers

When considering schools, one must pay attention to teachers. After all, teachers are the largest single budget item of schools, and many believe that they are the most important determinant of school quality. Yet research does not find a systematic link between teacher characteristics and student outcomes, leading to doubts about many current policy thrusts that are keyed to measurable attributes of teachers and their background.

The relevant research follows four distinct lines that relate in varying ways to teacher quality. At the most aggregate level and possibly the most influential, a variety of studies have traced changes over time in the salaries of teachers relative to those in other occupations. Going beyond that, a second level of studies relates pay and other characteristics of teaching jobs to the characteristics of teachers in different schools and districts and teacher turnover. A third line of research, following naturally from these, relates teacher characteristics to student performance. The failure to find a strong relationship between the contributions of teachers to student achievement and other outcomes, on the one hand, and teacher education, experience, and salaries, on the other, is inconsistent with the popular view of teachers as a key determinant of the quality of education. Finally, the fourth line of research appears to have solved this conundrum by demonstrating both the large impact of teachers on student learning and the lack of explanatory power of traditional quality measures.

The central focus of this paper is to relate these various bodies of research to a set of teacher quality policy initiatives. These proposals can be divided into three broad areas that are not mutually exclusive. First, because salaries of teachers have fallen relative to other jobs, some argue that an obvious move is simply to restore teacher salaries to their previous position in the earnings distribution to attract better teachers into the profession. Second, states should adopt more stringent qualifications for teachers such as mandatory master's degrees to improve quality. Salary increases are often, but by no means always, recommended along with more stringent qualifications to offset any possible negative impacts on teacher supply. Finally, an alternative set of policy proposals has taken a different tack. These typically advocate less strict instead of stricter requirements in combination with incentives for higher teacher performance and improved school personnel practices.

Research on Teacher Quality

While the evidence related to teacher quality is widely scattered, common themes do emerge. A key distinction is whether or not the investigations are related directly to student outcomes or simply rely upon a presumed relationship.

Aggregate Salary Trends

A starting point in the consideration of teacher quality is the evolution of teacher salaries over time. Figure 1 traces the wages of teachers age twenty to twenty-nine compared with those of other young college graduates between 1940 and 2000. The calculations, done separately by gender, give the proportion of nonteachers with a bachelor's degree or more who earn less than the average teacher. ¹

Over the entire time period since World War II, salaries of young female and male teachers have fallen relative to those for other occupations. However, we have shown that substantial gender differences are evident in the time path of relative salaries. ² For males, relative salaries fell between 1940 and 1960 but have remained roughly constant afterward. For females, relative salaries started out high—above the median for college-educated females—but then continuously fell. The changes are easiest to see for young teachers and college graduates, for whom the adjustment has been larger, but they also hold for teachers of all ages. In other words, the growth in late-career salaries has not offset the decline in salaries for younger teachers.