National Board Certification and Teacher Effectiveness: Evidence from a Random Assignment Experiment

The National Board for Professional Teaching Standards assesses teaching practice based on videos and essays submitted by teachers.  The current paper extends earlier research in a number of ways:  First, we compared the performance of classrooms of elementary students in Los Angeles randomly assigned to NBPTS applicants and to comparison teachers.  Second, we use information on each applicant’s NBPTS scaled score (not just whether the candidates achieved certification) to test whether the score is related to teacher impacts.  Third, we test the predictive value of each of the 10 subscores that make up the NBPTS’ scaled score.  Fourth, using data on pairs of teachers that were not randomly assigned, we compare estimated impacts without and without random assignment.  We find that students assigned to highly-rated applicants outperformed those in the comparison classrooms by more than those assigned to poorly-rated teachers.  Moreover, the estimates with and without random assignment were similar.  We make a number of suggestions for improving the predictive power of the NBPTS scaling process.