Research has also been conducted to determine whether master’s degrees, which approximately 50 percent of all teachers hold, influence student achievement.[40] This question is particularly relevant to teacher compensation. The single salary schedule, which operates in more than 95 percent of districts nationwide, offers teachers significant pay raises for earning a master’s degree.[41] As Dan Goldhaber has reported, "[D]ata from the National Center for Education Statistics show that salary schedules provide pay premiums of about 11 percent for master’s degrees and 17 percent for a doctorate."[42]

Despite the higher compensation provided to teachers with master’s degrees, the bulk of the evidence shows that, in fact, master’s degrees rarely appear to make teachers more effective.[*] Ferguson and Ladd found that master’s degrees had a very small positive effect on student achievement in math, but not in reading. In their analysis of school level inputs, they write: "A one-standard deviation increase in the fraction of teachers with a master’s degree (0.33 points) would increase student test scores by 0.026 standard deviations, about one-quarter of the effect of a standard deviation in teacher test scores."[†][43]

Hanushek and colleagues have repeatedly found, "[A] master’s degree has no systematic relationship to teacher quality as measured by student outcomes."[44] In his own study of teacher testing from 2006, which we discuss below, Dan Goldhaber recently confirmed Hanushek’s findings that master’s degrees have little impact on teacher quality. Goldhaber wrote: "Consistent with much of the educational productivity literature (for example, Hanushek 1986, 1997), there is little evidence that a teacher having a master’s degree (or higher) is a signal of teacher effectiveness."[45]

Goldhaber’s 2002 summary of other research findings on master’s degrees was somewhat more refined, however. He reported, "[T]he effect of degrees appears to hinge on the subjects that are taught and whether the degrees are specific to those subjects."[46] Goldhaber pointed to evidence that teachers with advanced coursework in math and science seem to be slightly more effective. He added, "Having an advanced degree in subjects outside of math and science, however, does not appear to affect student achievement."[47] Goldhaber did not address whether the apparently higher achievement of teachers with advanced math and science degrees had been driven by self-selection bias — in other words, the possibility that the degrees did not improve the teachers’ performance, but instead that highly effective math and science teachers tend to get subject-specific advanced degrees.

Until sophisticated "value-added" calculations entered mainstream education research during the last few years, high-quality studies on the impacts of advanced degrees on teacher effectiveness were in short supply.[**] Nearly all recent research, however, suggests that master’s degrees do not make for significantly better teachers.

[*] Other studies that assert that master’s degrees do not have a positive relationship with student outcomes include Donald Boyd et al., “The Effect of Certification and Preparation on Teacher Quality,” The Future of Children 17, no. 1 (2007); Stotsky and Haverty, “Can a State Department of Education Increase Teacher Quality? Lessons Learned in Massachusetts”; Loeb and Reininger, “Public Policy and Teacher Labor Markets: What We Know and Why It Matters.”

[†] The study did not appear to distinguish between the types of master’s degrees, meaning that an MA, MS and MEd were considered equivalent and represented by one variable (as a proportion of the staff).

[**] These “value-added” calculations will be described in more detail in “Using Value-Added Assessment to Define Teacher Quality."