Education Next: New Study Finds Teacher Certification Matters Little for Student Learning

Monday, November 20, 2006
STANFORD -- A new study published in the winter issue of Education Next finds virtually no difference in the average impact on student achievement between traditionally certified teachers in New York City and those who entered teaching without certification, through Teach for America (TFA) or through the city’s Teaching Fellows programs -- a finding that could have significant impact on the debate over the reauthorization of NCLB and the law’s “highly qualified” teachers provision.
The study shows that students in grades 4 through 8 learn much more -- as much as a full year more -- from high performing teachers compared with low performing teachers, but that there is, on average, little difference among teachers entering New York City schools through different certification routes.
Students assigned to TFA teachers learned slightly more (2 percent of a standard deviation) in math than similar students assigned to traditionally certified teachers. Students whose teachers came from the Teaching Fellows program learned slightly less (1 percent of a standard deviation) in reading than similar students with traditionally certified teachers, but this difference faded as the teachers gained experience. Both these differences were small compared with the differences in effectiveness among teachers with the same certification status.
The authors recommend that school districts pay less attention to teacher credentials and more attention to monitoring teachers’ performance during the first two years of teaching so that effective teachers are retained while ineffective ones are not.
The study, by economists Thomas J. Kane or Harvard University, Jonah E. Rockoff of Columbia Business School, and Douglas O. Staiger of Dartmouth College, peer-reviewed for publication in Education Next, answers the question of whether certification ensures highly effective teachers in the classroom.
In their study, the researchers used the New York City Department of Education’s (NYCDOE) detailed database of information on student achievement, which links individual students and teachers by classroom. Uncertified and alternatively certified (AC) teachers are more likely to work in urban areas with low-income and low-achieving students. Because New York City is a major employer of uncertified and AC teachers, its data were an exceptional resource for the study. The primary alternative certification program is the NYC Teaching Fellow program. Between 1999 and 2005, more than 50,000 new teachers were hired in New York schools; more than 50 percent were uncertified or AC teachers. 
Kane, Rockoff, and Staiger looked at NYCDOE’s math and reading data for grades 3 through 8 from 1998 to 2005, comparing the impact of uncertified teachers, AC teachers from the city’s Teaching Fellows program, Teach for America (TFA) participants, and traditionally certified teachers. The NYC DOE data include identification numbers for students’ math and reading teachers, enabling a student to be matched to his or her teacher. Student data include test scores, race and ethnicity, eligibility for the federal free and reduced-price lunch program, status as an English as a second language or special education student, and attendance record, allowing the researchers to take these characteristics into account when evaluating a teacher’s contribution to student learning.
Kane, Rockoff, and Staiger also investigated how teaching effectiveness improves with experience among these groups. They found that uncertified and AC teachers learn somewhat more from experience in their initial years. Teaching fellows showed more improvement in both math and reading instruction after the first two years than did traditionally certified teachers. After two years on the job, a teaching fellow’s students would score 3 percent of a standard deviation higher on average in math and reading than the traditionally certified teacher’s students. Uncertified math teachers’ gains from experience also outpaced those of traditionally certified teachers. Given the same initial effectiveness as a traditionally certified teacher, an uncertified third-year teacher’s students would score 3 percent of a standard deviation higher on average in math.
The researchers suggest that states need to develop the infrastructure for assessing the performance of novice teachers during their first few years on the job. The greatest potential for school districts to improve student achievement lies in retaining those teachers who are most effective during their first years of teaching, not in regulating minimum qualifications for new teachers. 
Although alternative certification programs have often been criticized for high turnover, Kane, Rockoff, and Staiger found that teaching fellows actually have slightly lower attrition rates in the first two years than traditionally certified teachers and that after five years the attrition rates are, in fact, about the same -- approximately 50 percent for both groups. Teachers who were initially uncertified are only slightly less likely to stick around -- about 45 percent are still teaching in their fifth year. 
Not surprisingly the authors found higher attrition among TFA corps members (reflecting their minimum commitment of two years).  Because the payoff to teaching experience was rather modest, however, they estimate that the negative impact of higher turnover on student achievement (i.e., hiring more inexperienced teachers) was sufficiently small that, at least in math, it was completely offset by the positive impact of TFA corps members during their employment.
The authors write, “By shifting the focus away from ‘qualifications,’ we are not proposing to open the floodgates into teaching. Instead, we simply want to move the dam further downstream from the time of initial recruitment, and postpone assessments of teacher’s effectiveness for a year or two until districts have much more useful information about which teachers are performing well and which are performing poorly. Only by shifting the focus away from ‘qualifications’ and toward assessing teachers’ performance in their initial years can we hope to live up to the aspirations of the No Child Left Behind Act.”
Read “Photo Finish” in the new issue of Education Next, now online at
Thomas J. Kane is professor of education and economics at the Harvard Graduate School of Education. Jonah E. Rockoff is an assistant professor of economics and finance at Columbia Business School. Douglas O. Staiger is professor of economics at Dartmouth College.
Education Next is a scholarly journal published by the Hoover Institution that is committed to looking at hard facts about school reform. Other sponsoring institutions are the Harvard Program on Education Policy and Governance and the Thomas B. Fordham Foundation.