In a blog post for The Brown Center on Education Policy, Thomas Kane proposes a new definition for an “effective” teacher: one whose “predicted impact on students exceeds that of the average novice teacher.”
The former director of the Gates Foundation’s Measures of Effective Teaching project, Kane says that one of the advantages of his proposed definition is it clarifies the trade-offs involved in retaining or replacing staff members. He writes:
...it makes explicit the decision a principal implicitly makes every time he or she retains a non-probationary teacher—to forego the opportunity to recruit a novice teacher as a replacement. Would an NFL coach give up a future draft pick for an experienced player he expects to perform worse than the average rookie? Not if he were trying to win. Would a principal promote or retain a teacher with expected performance below that of the average novice? Not if he or she had the students interests at heart.
A commenter on the post makes another sports comparison: “Seems to be the educational equivalent of WAR (Wins Above Replacement).” For those not familiar with WAR (like me before a bit of Googling), it’s a way to calculate a baseball player’s worth by determining how many more wins he would contribute to a team than would a replacement-level player—someone just up from Triple-A. ESPN now includes the wonky calculation on its stat pages.
Comparing Kane’s definition to WAR seems fair enough to me. However, as I read about WAR, I’m starting to wonder whether it’s an even more apropos analogy for another part of the teacher-policy debate: value-added measures, which use student test scores to judge a teacher’s impact.
According to Fansgraphs, WAR is “an attempt by the sabermetric baseball community to summarize a player’s total contributions to their team in one statistic. You should always use more than one metric at a time when evaluating players, but WAR is pretty darn all-inclusive and provides a handy reference point.” Likewise, in education, value-added measurement seeks to summarize a teacher’s total contributions to a group of students in one metric. While there’s now widespread agreement that teacher evaluations should include multiple measures, proponents of VAM tend to see it as “pretty darn all-inclusive.”
Further, Baseball-Reference.com states, “There is no one way to determine WAR. There are hundreds of steps to make this calculation, and dozens of places where reasonable people can disagree on the best way to implement a particular part of the framework.” Sound familiar? See previous coverage of the many VAM formulas and the inconsistencies between them here and here and here.
Now that I’m thinking about it, maybe I’ll rewatch “Moneyball” this weekend to see what other education-policy analogies are lurking ...
A version of this news article first appeared in the Teaching Now blog.