WASHINGTON, D.C. – The teacher rating system used in D.C. Public Schools is known as one of the most aggressive evaluation programs in the country.

A new study finds it’s one of the most effective, too.

Researchers at Stanford University and the University of Virginia have concluded that D.C. Public Schools’ mixed approach to improving teacher performance – namely, huge financial incentives coupled with the threat of being fired – is yielding big increases in teachers’ classroom performance.

MORE NEWS: From Classroom to Consulate Chef: Culinary Student Lands Dream Job at U.S. Embassy in Paris

The job review system, known as IMPACT, has also resulted in the termination of 500 low-performing teachers and the voluntary exit of many other borderline educators since its inception in 2009, reports USAToday.com.

The study’s findings are a huge vindication of former D.C. Schools Chancellor Michelle Rhee, whose unflinching support of IMPACT contributed to her ouster in 2010.

The study also deals a blow to teacher union leaders who dispute the effectiveness of linking educators’ pay to their classroom performance. Unionists also reject merit pay plans on the ridiculous premise that all teachers are equal and should be treated the same.

Phys.org explains the stakes of the D.C. teacher evaluation plan:

“High-performing teachers – as assessed by IMPACT – earn an annual bonus of as much as $25,000 as well as an opportunity for similarly large and permanent increases in their base salaries. In contrast, teachers who are unable to achieve an ‘effective’ rating after two years are dismissed.”

The study finds that teachers on the brink – either of being fired or of qualifying for a huge bonus – showed the biggest jump in their measured performance, Phys.org reports.

MORE NEWS: Know These Before Moving From Cyprus To The UK

Researchers explain that while other states have used financial incentives in their teacher evaluation plans, they don’t work very well because the rewards are too small and the job reviews rely too heavily on student test scores – an area teachers feel they have little control over.

D.C. schools’ IMPACT plan, however, determines a teacher’s rating “on multiple measures,” including five classroom observations a year that are “rated on nine explicit criteria that the district uses to define effective instruction, including how well they explain concepts and if they check for student learning,” Phys.org reports.

“IMPACT appears to have been comparatively successful in defining what teachers need to do in order to improve their scores and providing corresponding supports,” says study co-author James Wyckoff. “Evaluations and incentives are likely to have little effect if teachers lack the knowledge and support to act on the information the evaluations provide.”