Teacher Certification Raises Salaries but not Quality
...state-mandated testing for teachers increases their wages by 3 to 5 percent but has no observable effect on their quality.
As of 1999, 43 states required prospective teachers to pass a certification test. Proponents of testing say that it establishes minimum quality standards. Economists have long been skeptical of such claims, pointing out that there is little evidence that licensing requirements create benefits for consumers and quite a bit of evidence to suggest that they create barriers to entry that raise pay rates in the professions that they protect.
In Does Teacher Testing Raise Teacher Quality? Evidence From State Certification Requirements (NBER Working Paper No. 9545), co-authors Joshua Angrist and Jonathan Guryan estimate the effect of state teacher testing requirements on teacher wages and teacher quality. Preparation for teacher certification tests is costly. If private sector jobs with similar wages but less costly entry requirements are readily available, then the best applicants may choose those over public school teaching, lowering the average quality of the new teacher pool. Using data from the Schools and Staffing Survey, the authors find that state-mandated testing for teachers increases their wages by 3 to 5 percent but has no observable effect on their quality, as measured by the average SAT score of an individual teacher's undergraduate institution.
Consistent with their finding of no quality benefit from testing teachers, the authors point out that "while occupational licensing requirements are widespread and apparently increasing, most skilled workers in the private sector are still not subject to formal licensing or testing."
-- Linda Gorman