“When aspects of the school context—for example, a principal who is an ineffective instructional leader, a school that lacks a consistent disciplinary code—are partly, or largely to blame for poor performance, efforts to measure and strengthen individual teacher effectiveness are unlikely to be adequate remedies in themselves”

—Gillian Kiley, “School environment key to retaining teachers, promoting student achievement, study finds” on Phys.org

Check out the study linked to above, which uses NYC school survey data. Certainly confirms everything this blog is premised upon.