Thompson: A Shoddy Study On Teacher Retention

The Washington Post's Emma Brown, in Study Chides D.C. Teacher Turnover,  reports that the TNTP, which was founded by Michelle Rhee, asserts that the D.C. schools do not retain enough "irreplacable" teachers but they are doing a better job of removing ineffective ones.  

The TNTP report, titled Keeping the Irreplaceables in D.C Public Schools, acknowledges one problem - that Rhee's IMPACT evaluation system is the fourth most important reason why top teachers leave.   And, as Dana Goldstein notes, up to 40% of D.C. teachers turned down IMPACT bonuses in return for giving up their seniority protections -- indicating a lack of trust in the district.

How did the TNTP try to address the all-important question of whether D.C. is unfairly evaluating teachers in high-poverty schools?  That's where the real action is.

The TNTP report uses D.C.'s value-added data - which is the most questionable part of IMPACT - as evidence that IMPACT as a whole is fair to teachers in tough schools. And, as the Shanker Institute's Matthew DiCarlo explains, such circular reasoning is only one of the TNTP's methodological flaws. DiCarlo notes that "there are virtually no low-rated teachers in the schools within the lowest-poverty quintile, and about three times as many highly-rated teachers as in the other groups." 

DiCarlo further explains that the TNTP's methodology is worrisome because  it ignores "virtually every prior study" that has found "that teachers who exit do tend to be less effective (in terms of value-added) than those who remain."  Worse, it is driven by the TNTP's focus on “'low-cost retention strategies,' such as 'high expectations,' and principals encouraging teachers to stay and recognizing their work."

It would be nice if Michelle Rhee, and the organization she founded, were correct and there were cheap and easy ways of building a teacher corps capable of overcoming intense concentrations of trauma and poverty.  But, even a researcher as polite as DiCarlo concludes, that the TNTP analysis "doesn’t tell us much of anything about the effects of recent DCPS policy changes." (emphasis by DiCarlo)-JT(@drjohnthompson) Image via.