A new study by Jason A. Grissom and Brendan Bartanen of Vanderbilt University examines the impact of principal effectiveness on teacher turnover. It’s well established that better school leadership leads to lower average turnover, but as the authors write, “all teacher turnover is not created equal.”

Grissom and Bartanen used data on all public education personnel in the state of Tennessee from 2012 to 2017. To gauge teacher effectiveness, they relied on observation and student growth scores. And for principals, they looked to evaluations by superiors, as well as surveys from teachers.

Tennessee’s statewide educator evaluation system, the Tennessee Educator Acceleration Model (TEAM) began in the 2011–12 school year and produced the data used in this study. This means that principals in Tennessee may have had better information to use when evaluating teachers than their peers in other states.

Grissom and Bartanen offer descriptive findings that add context to their examination of whether principals affect teacher turnover. Most noteworthy is that, in general, less effective teachers are more likely to turn over: 37 percent of the teachers in the least effective band turned over, compared to just 11 percent of teachers in the most effective range. Overall, 13 percent of teachers turned over each year.

As for the big question, the study echoes previous research, finding that principals with greater effectiveness have lower teacher turnover in their schools. Specifically, a 1 standard deviation (SD) increase in principal effectiveness is correlated with about a 5 percent change (0.5 percentage points) in teacher turnover.

Grissom and Bartanen also find evidence of “strategic retention,” wherein good principals are better at keeping effective teachers and getting rid of less effective teachers. A 1 SD increase in the superior rating (the superintendent’s rating of the principal) is associated with a 1.3 percentage-point decrease in turnover among teachers with comparatively high observation and student growth scores, and a 2.3 percentage-point increase in the likelihood of turnover among teachers with low marks. Their results also suggest that observation scores, rather than measures of teacher effectiveness derived from student test score growth, drive the patterns of strategic retention. This is in line with prior literature that says principals rely most on observation, and less on value-added measures because they’re opaque.

The effects Grissom and Bartanen detailed are strongest in suburban schools, perhaps because there’s more demand to teach in those areas. And indeed, if no one else wants to teach in your school, you probably shouldn’t be nudging teachers out. As the authors put it, “principals in more advantaged schools may worry less about finding quality replacements for teachers who leave, leading them to focus on pushing out low performers.”

The study’s findings are not exactly shocking. Good leaders at any kind of organization do the best with what they have, while also trying to improve their staff over time, hiring and promoting good people and sometimes nudging others towards the door. But it does demonstrate yet again that leadership matters.

SOURCE: Jason A. Grissom and Brendan Bartanen, “Strategic Retention: Principal Effectiveness and Teacher Turnover in Multiple-Measure Teacher Evaluation Systems,” American Educational Research Journal (September 2018).

Adam Tyner is associate director of research at the Thomas B. Fordham Institute, where he helps develop and manage Fordham’s research projects. Prior to joining Fordham, he served as senior education analyst at Hanover Research, where he executed data analysis projects and worked with school districts and other education stakeholders to design custom studies. Adam has also spent several years leading classrooms, teaching…

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