teacher testing & teaching quality

By requiring teachers to pass tests or receive certifications, we can ensure that public school teachers obtain some minimum level of education and knowledge. Does imposing such requirements increase student performance?

Joshua D. Angrista (MIT) and Jonathan Guryanb (U Chicago) find no evidence that increasing teacher requirements increases teacher quality. This may be because the increased requirements makes it more difficult to become a teacher, which likely affects the types of students who choose to become teachers. It also forces schools to hire along this one-dimension, even if the school believes that an uncertified teacher would make the better teacher.

What's more, the authors show that the increase in requirements increases teacher wages (without increasing teacher quality). This is unsurprising since increasing teacher requirments likely decrease the supply of teachers--in the labor market this means higher wages. This article suggests that increasing teacher teasting and certification requirments increases the cost of education without increasing the quality of education.

link to the article