Association for Public Policy Analysis & Management

Many states have recently enacted substantial reforms to the teacher labor market including changes to teacher tenure, evaluation, and collective bargaining. Generally, these reforms are aimed at improving teacher quality by empowering school and district leaders to make effective personnel decisions. However, some teacher advocates have viewed these reforms as a “war on teachers” and fear harmful impacts on the teacher work force that might affect students as well. While there is growing evidence related to the impacts of these reforms on teachers, very little is known about the impact on student achievement.

To help strengthen that body of evidence, we test whether individual student achievement was affected by a set of reforms in Michigan that increased evaluation requirements for public school teachers, reduced tenure protections, and restricted teachers’ unions’ abilities to collectively bargain. Specifically, we assess whether achievement improved overall or in particular types of districts.

We examine these questions with multiple specifications of a comparative interrupted time series (CITS) framework, using data on all public school students in Michigan from 2005-06 to 2015-16. We exploit three main determinants of treatment exposure: timing of exposure, exposure based on pre-reform contract restrictiveness, and differential exposure based on public school sector. These three approaches are described below.

First, Michigan traditional public school teachers were not subject to the main slate of reforms until their districts’ pre-reform collective bargaining agreement (CBA) expired. Therefore, our preferred specification exploits the plausibly exogenous timing of pre-reform CBA expiration dates to identify the causal effect of the reforms on student achievement. Alternatively, it could be that districts were also impacted immediately when the law was passed, so we estimate a purely descriptive interrupted time series (ITS), assuming all districts were treated in 2011. Secondly, traditional public school (TPS) districts with CBAs that placed more restrictions on school leaders’ ability to make personnel decisions would have been subject to larger changes once these reforms were implemented and these teacher protections were removed. Thus, we use a continuous measure of pre-reform CBA restrictiveness as an additional measure of reform exposure. Finally, only one component of these reforms, teacher evaluations, was directly applicable to charter school teachers, so as a specification check, we use students in charter schools as a comparison group for the arguably more treated traditional public school sector.

In addition to testing overall impacts on student achievement, there is reason to expect differences across districts. Cowen, Brunner, Strunk, and Drake (2017) find that teacher attrition only increased in relatively disadvantaged districts, so it is possible that student achievement impacts may be isolated as well. Thus, we test for differential impacts on students with more low-income students, more minority students, more English language learners, and lower performing students.

Overall, we find that student achievement was largely unaffected by these labor market reforms. Thus, despite the debate over whether a “war on teachers,” harmed students, changes to teacher labor markets in Michigan did not appear to directly affect student outcomes.