Study: Teachers Unions Raise Teacher Quality And Increase Kids’ Educational Attainment

A new study by Eunice S. Han, Wellesley College, finds that teachers unions raise study and teacher quality, and that attacks on teachers unions intended to weaken them, are likely to have detrimental effects.

From the conclusion

This study examines the relation between teachers unions and teacher turnover and assesses union effects on US public schools. The significant contributions of this study to literature include the provision of a theoretical framework of unions’ roles in both voluntary and involuntary teacher turnover, the diverse measurements of unionism from all 50 US states, the controls for various district-specific and teacher-specific demographics available from district-teacher matched data, and the use of panel data.

A simple two-period job matching model with positive renegotiation costs predicts that teachers unions raise the dismissal of low-quality teachers because higher wages give districts a greater incentive to select high-quality teachers but lower the attrition of high-quality teachers, as they negotiate higher wages for teachers. The unique district-teacher matched panel data enable me to utilize the within-state and within-district variation of unionism and instrumental variable regressions to identify the union effects on the educational system.

The empirical evidence confirms these predictions. I find that districts with strong unionism dismiss more underperforming teachers and have lower teacher attrition than districts with weak unionism.

Through the dynamics of teacher turnover, unions ultimately raise teacher quality, as unionized districts can better retain good teachers and dismiss more underperforming teachers. Two pieces of empirical evidence support this hypothesis: districts with strong unionism have more teachers with stronger qualifications and lower dropout rates than districts with weak unionism. I also find that the recent legal change weakening unionism in four states affects the teacher turnover pattern and teacher quality negatively, confirming unions’ positive role in the US educational system.

This research, therefore, suggests that restricting the legal boundary for unions’ activities may not be the appropriate approach in improving educational outcomes. Rather, promoting union-friendly environments may create more encouraging economic conditions for teachers and provide districts with incentives to select better teachers, eventually raising teacher quality.

Here's the full study