STOP THE PRESSES! This is a fascinating study with stunning results: to optimize student outcomes, school systems should only keep the top 20% of probationary (new) teachers because "There are enormous costs to having mediocre teachers burdening the school system, and once they get their union cards, we're stuck with them for decades. The benefits of keeping only the superstars is enormous, such that it's better to risk accidentally losing some of the good ones than to have deadwood sticking around forever.":

When they ran the numbers, the answer their computer spat out had them reviewing their work looking for programming errors. The optimal rate of firing produced by the simulation simply seemed too high: Maximizing teacher performance required that 80 percent of new teachers be fired after two years' probation.

After checking and rechecking their analyses, Staiger and Rockoff came to understand why a thick stack of pink slips are needed to improve schools. There are enormous costs to having mediocre teachers burdening the school system, and once they get their union cards, we're stuck with them for decades. The benefits of keeping only the superstars is enormous, such that it's better to risk accidentally losing some of the good ones than to have deadwood sticking around forever.

Is an 80 percent dismissal rate practical? One issue is whether there would be enough new recruits to replace all the teachers you'd be firing. Teach for America has been able to fill its ranks with Ivy League graduates year after year, so we know there are lots of college grads who are willing to devote at least a couple of years of their lives to teaching, and 63 percent of TFA alumni remain in the field of education afterward. If the teaching profession gains greater status and prestige, perhaps many more would choose teaching as a career rather than moving on to more lucrative jobs at Goldman Sachs or McKinsey. And in 1997, the L.A. school system was able to triple its rate of hiring, bringing in additional recruits with no discernible decline in the quality of those hired. Then again, while TFA and the L.A. Department of Education may have a steady supply of applicants, that doesn't much help schools in small-town America, where recruitment is more of a challenge.

And, of course, another issue is politics. It's hard to reconcile an 80 percent dismissal rate with the existence of teachers' unions: Pushback from unions and the government leaders who rely on their support have largely managed to prevent any breach of teacher job security thus far. (Although, D.C. Schools Chancellor Michelle Rhee may be on her way to cutting a tenure-ending deal with Washington's union.)

This is something that Staiger and Rockoff understand. Their point isn't that we can or should fire 80 percent of new hires, but that their work should be seen as a "thought experiment" on the extreme measures that would be required to really improve American education, provided we can't figure out how to find better teachers at the get-go or develop reliable methods of improving teachers once they're in the system.

A copy of the slide presentation is posted at: www4.gsb.columbia.edu/rt/null?&exclusive=filemgr.download&file_id=733883&rtcontentdisposition=filename%3DStaiger

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