New York’s Department of Education is beginning to measure the performance of thousands of elementary and middle school teachers based on how much their students improve on annual state math and reading tests, the New York Times reported last week. A joint letter to NYC teachers from Chancellor Joel Klein and UFT President Randi Weingarten explained the data is intended to “empower teachers with information useful in our teaching. In this same vein, the letter expressly prohibits the use of that information for evaluating teachers, in both annual ratings and tenure decisions.”
When the plan first came up in February, Ed Sector’s Kevin Carey wrote a much-discussed op-ed in the New York Daily News, comparing value-added data to the pioneering work done by maverick baseball general manager Billy Beane. The subject of Michael Lewis’ 2003 book, Moneyball, Beane has often managed to keep his small-market Oakland A’s competitive with deeper-pocketed teams by rejecting conventional baseball wisdom in favor of data-driven decision-making. “By crunching numbers without prejudice, Beane discovered that certain statistics that really mattered on the field, like on-base percentage, were being hugely undervalued in the player job market,” Carey wrote. “While scouts and other executives made decisions based on personal bias and flawed perceptions, Beane kept to the statistical bottom line.” Seen through this lens, the hope and promise is that we can find equivalents to on-base percentage in teacher performance that drive student achievement.
The Moneyball comparison, however, strikes me as a potentially dangerous analogy. Here’s why: Players are to baseball teams as students — not teachers — are to schools. Teachers succeed by getting the best performances from their students. Their closest counterparts in baseball are managers and coaches. Baseball executives like Billy Beane do not use data to help ordinary players over-perform. They use data to replace underperformers with overachievers. To run a school like Billy Beane runs the Oakland A’s would mean regularly replacing low-scoring students with high-scoring students.
That would be one way to close the achievement gap. Continue reading ‘Teacher Quality, Unintended Consequences, and the Baseball Achievement Gap’









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