New York City just killed its merit pay program for teachers. The program was expensive—top performers were eligible for bonuses of $1,500 to $3,000, for a total of $56 million in outlays over the last three years—and it wasn't getting results. Despite the additional millions at stake, teachers in the schools where merit pay was available continued to do the same old stuff. Weird, right?

The New York press (and critics of merit pay as a tool for school reform) jumped all over the news, citing a just-released RAND study as evidence that alone among all of humanity, teachers are somehow immune to monetary incentives. But the same study included this key tidbit (via Public Sector Inc.):

"a majority of the schools disseminated the bonuses equally among staff, despite program guidelines granting school committees the flexibility to distribute the bonus shares as they deemed fit."

And why did that happen? From The New York Times:

In New York, the bonus program operated on a schoolwide basis, not an individual-teacher level, as a result of an agreement between the Education Department and the teachers' union, the United Federation of Teachers.

In short: Meritorious teachers did not actually make a single dollar more than their slacker colleagues.

The failure of the NYC program reveals very little about whether merit pay can work—and a great deal about the power of teacher's unions.

Via the Twitter feed of @benboychuk.