District of Columbia's controversial teacher evaluation program is getting many low-rated teachers out of the system and improving performance of those who stay. High-rated teachers' performance is improving, too.

The controversial teacher evaluation system used by District of Columbia schools seems to be working, according to a new study from the National Bureau of Economic Research. The study showed that using a carrot and a stick — merit pay and threat of firing — motivated improvements by weak teachers and spurred effective teachers to even higher performance levels.

Hundreds of teachers have been fired since the evaluations were implemented four years ago, the Washington Post reported. The study found that the punishments and rewards in the evaluation system inspired two groups of teachers to improve significantly more than others: low-scoring teachers under threat of firing and high-scoring teachers within striking distance of a substantial merit raise, the story continued.

“The study is among the first attempts to understand the effects of the District’s teacher evaluation system, known as ­Impact. Then-Chancellor Michelle Rhee introduced the system in 2009, and it was among the first in the nation to link teachers’ job security and compensation to student test scores,” the Washington Post reported.

The findings are unlikely to quell criticism of the closely watched evaluation system, according to USA Today, which noted that it allows the District of Columbia to fire teachers rated “ineffective” after just two years. High-performing teachers can qualify for an annual bonus of up to $25,000 or more for their entire careers.

“The researchers found that Impact had an impact within two years: teachers with one ‘minimally effective’ rating were much more likely than others to quit, but those who were rated ‘highly effective’ stuck around and earned higher scores,” the story said.

Teachers just under the “effective” threshold improved more than those just above it, suggesting that the threat of firing had the intended effect, USA Today said. And, “highly effective” teachers who saw a bonus looming within reach also improved substantially.

The study does not look at whether improvements in teachers’ scores translated into more learning for their students, noted Education Week blogger Stephen Sawchuk.

D.C.’s Impact evaluation system rolled out in the 2009-10 school year. It relies on a complex mix of factors for scoring teachers, including multiple observations and measures of student achievement, Sawchuk wrote.

“Though Impact has won accolades in policy circles, some teachers have been less happy with the system,” he continued. “In surveys and focus groups, they have complained about feeling monitored, and harbor concerns that it’s harder for teachers in the most challenging school to get top scores on the evaluation.”

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