The Myth of the Master's Degrees

The source: “Teacher Credentials Don’t Matter for Student Achievement” by Charles Clotfelter, Helen Ladd, and Jacob Vigdor, as summarized in The NBER Digest, Aug. ­2007.

In many school districts, slogging through extra college courses to get a master’s degree boosts a teacher’s annual salary by $2,000 or more. But an extra diploma doesn’t significantly improve student achievement. In some cases, elementary school pupils taught by teachers with advanced degrees actually do worse, write Duke University economists Charles Clotfelter, Helen Ladd, and Jacob ­Vigdor.

Most Americans agree that the quality of their child’s teacher is crucial to learning, but teacher quality is notoriously hard to measure. The Duke economists studied the test scores of about 75 percent of all North Carolina third, fourth, and fifth graders between 1994 and 2003. They found that a teacher’s increasing experience and acquisition of a “regular” teaching license rather than an “other” license (given to those who do not meet all official requirements) made a positive difference on students’ test scores, particularly in math. Teachers with 21 to 27 years of experience were most effective, they ­found.

But teachers who earned a master’s degree before they began their career or during their first five years of teaching were no better at raising student achievement than teachers with only an undergraduate degree. Those who got an advanced degree more than five years after they started teaching appeared to be “somewhat less effective” on average than those who did not get one at all, the researchers ­found.

The authors  question whether the higher salaries given to teachers with master’s ­degrees—­not to mention the graduate education subsidies offered by some ­districts—­are well spent. In  ascertaining why master’s degrees don’t matter, the answer could well be a var­iation on Bill Clinton’s old cam­paign slogan: “It’s the teacher, stupid.”