Study: Teachers' unions don't provide more pay

Teachers' unions have little impact on a school district's allocation of money, including teacher pay and spending per student, according to a study published this month in the Journal of Labor Economics.

Using data from school districts in Iowa, Indiana and Minnesota, Cornell economist Michael Lovenheim compared district spending trends before and after each district became unionized. He also compared trends between union and non-union districts. Specifically, his analysis looked at teacher pay, spending per student, number of teachers employed and student-teacher ratio.

"My results indicate unions have no impact on teacher pay, either in the short or long run," Lovenheim writes. "I also estimate little effect on per-student expenditures, particularly in the long-run."

Unionization does increase the number of teachers that a district employs, the study found. But those increases were offset by increases in student enrollment. As a result, there was no difference in student-teacher ratio attributable to unionization.

The study also found that unionization has no effect on student drop-out rates -- an indication that unions do not improve teacher productivity or educational outcomes, Lovenheim says.

The findings are at odds with previous studies on teachers' unions, most of which have found that unions do increase teacher pay and district spending. But Lovenheim argues that those studies used inaccurate data on which districts were actually unionized and when those unions became active.

To correct this, Lovenheim gathered certifications of union elections from state Public Employment Relations Board offices. The certifications mark the exact time when teachers in each district elected someone to represent them at the bargaining table. Knowing exactly which districts unionized and when is essential for an accurate analysis, Lovenheim argues.

The results raise the question: If teachers' unions have no clear impact on such a wide swath of measures, why unionize at all?

"One possible answer to this puzzle is teachers perceive organization increases their pay," Lovenheim writes. "Indeed, when talking to union members during this study, wage increases were the most commonly mentioned benefit of unionization, in contrast to what this analysis shows."

It is also possible that unions provide benefits in working conditions such as hiring and firing rules, pay structure or promotion. "There is anecdotal evidence teachers' unions provide these benefits?, but I lack the data to test for such effects," Lovenheim writes.

Michael Lovenheim, "The Effect of Teachers' Unions on Education Production: Evidence from Union Election Certification in Three Midwestern States." Journal of Labor Economics 27:4 (October 2009).

Since 1983, the Journal of Labor Economics has presented international research that examines issues affecting the economy as well as social and private behavior. The Journal publishes both theoretical and applied research results relating to the U.S. and international data.

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October 20, 2009