Last week, the New York City Department of Education released performance data for the district’s 18,000 public school teachers.  According to an article in Governing,

The reports rank individual teachers based on their students’ performance in math and English over a five-year period, concluding with the 2009-2010 school year. According to the Times, a spokesman for the department said that more than 500 teachers ranked in the bottom 5 percent for two or more years, while nearly 700 placed consistently in the top 5 percent.

The district was able to rank teachers using value-added scores, a method of calculating students’ academic growth from one point in time to another.  North Carolina’s public schools also calculate and record value-added scores for teachers, but state officials have not released so-called EVAAS (Education Value Added Assessment System) data to the public.

The release of the NYC value-added data  increases our understanding of the variations in teacher effectiveness from school to school.  Contrary to the claims of the Left, high percentages of ineffective teachers were not clustered in schools with a high percentage of low-income and/or low-performing students.  Rather, preliminary analyses suggest that bad and good teachers were evenly distributed across schools.