Measuring Teacher Quality

The lack of reliable indicators of teacher quality has hindered researchers' attempts to answer the central policy question: How do alternative policies affect the supply of effective teachers? Most studies have focused on the role of incentives in the occupational decisions of all teachers, potential teachers, and former teachers and on how their decisions affect the total pool of college graduates willing to teach. These studies are useful in that they document that incentives do affect career decisions, but they do not directly address the central question of how policies affect the quality of the stock of teachers.

One assumption used in many studies of teachers' career patterns is that academic talent is a good indicator of teaching effectiveness. The assumption rests on the results of studies showing that measures of teachers' academic talent are positively related to their students' test score gains. Some of these studies use teachers' scores on standardized tests as the measure of academic talent; others use indicators of the quality of the undergraduate college the teacher attended (Ehrenberg and Brewer, 1994, 1995; Ferguson, 1991; Hanushek, 1972; Summers and Wolfe, 1977; Winkler, 1975).

The value of the assumption that college graduates' academic talent predicts their effectiveness as classroom teachers is that many databases that track college students' careers contain measures of academic talent. The assumption makes it possible to interpret the results of studies exploring the career decisions of academically talented college graduates as evidence of the factors affecting the career decisions of effective teachers.

This assumption has intuitive appeal. Teaching is a complex job, and it makes sense that academically talented college graduates have an advantage in learning the many skills required to teach well. However, one should be cautious in equating academic talent with teaching effectiveness. The evidence supporting this assumption comes from databases in which academically talented teachers went through the same type of preservice training that other teachers did. There is no reason to believe that the preservice training received by the academically talented teachers in these studies was less intensive than that received by teachers with lower levels of academic talent. In fact, it might have been of higher quality since the academically talented teachers tended to attend colleges with more financial resources than the colleges attended by less academically able teachers.

In recent years public and private policies have been introduced to attract academically talented college graduates to teaching, in part by reducing the amount of preservice training that participants must undergo before beginning classroom teaching. Examples include alternative certification (licensing) programs in a number of states and the highly publicized private program, Teach for America (TFA). These programs are attractive to academically talented college graduates who intend to teach for a few years and then pursue other, more lucra-

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