Hanushek is nothing if not a believer in the unconditional truth emanating from his regression equations. But of course, those equations have not always been as clear cut in their implications as some might believe. In 1997, Hanushek published an article in which he argued that a summary of dozens and dozens of correlation studies proved that teacher experience is unrelated to their students’ achievement—the financial implications being obvious. He presented the following summary of studies that investigated the relationship (in terms of regression coefficients) between student achievement and their teachers’ “years of experience.”
Although a statistically significant regression coefficient for “teacher experience” was six times more likely to be positive than negative, Hanushek nonetheless read the results as negative for the effects of teacher experience on achievement. “Importantly, … 71% [of the regression coefficients] still indicate worsening performance with experience or less confidence in any positive effect,” he wrote.
The logic of this conclusion is illusiveno; it makes no sense. Of results that reach statistical significance, 85% (60/70) are positive; students of more experienced teachers achieve at higher levels. Of the statistically non-significant results that can be determined, 55% are positive, but fail to reach conventional levels of significance. Hanushek creates an impression of no effect of teacher experience by lumping together the category (1) “indicative of worsening performance or less confidence of beneficial performance” all significant but negative coefficients (5%), (2) all nonsignificant coefficients whether positive or negative (30% + 24%) and, (3) remarkably, the 12% of the coefficients that were so incompletely reported that it could not be determined whether they were positive or negative. The treatment of these data is hardly even handed. By such logic, ten “positive studies,” “no negative studies” and 100 studies so poorly reported that the results could not be discerned would lead Hanushek to a conclusion of no confidence in a positive result. My reading of these results is much different from Hanushek's. Regression studies have generally shown a positive relationship between teacher experience and student achievement. Period.
So if Hanushek’s performance in reviewing the research on teacher experience and student achievement is as shaky as this, how does he perform in court on matters closely related? Aaron Pallas, in his blog "A Sociological Eye on Education" recently wrote on that question.
I was reminded of a school finance court case in Maryland some 30 years ago [Hornbeck; I testified in that case on the role of class size and student achievement ~GVG] for which I served as a consultant. … The poorest districts in the state, including Baltimore City, were suing the state to force it to equalize school funding. The state … hired noted economist Eric Hanushek to testify that money doesn’t make a difference in student outcomes. I was hired to prepare questions for cross-examination that might discredit Hanushek’s testimony.Now thirty years later, Hanushek is still telling courts that money doesn’t matter. (Linda Darling-Hammond probably made the most incisive comment on the “money doesn’t matter” position when she said, “If money doesn’t matter, why are the rich trying so hard to hold onto it?”) He testified in the recent Colorado school finance case (Lobato vs State of Colorado) once again that money doesn’t matter. Only this time, a Colorado judge had little sympathy for counter-intuitive social science stuff. In her 189-page ruling deciding in favor of the plaintiffs, Judge Sheila Rappaport commented thusly on Hanushek’s testimony:
A friend … suggested a novel line: If, as Hanushek argued, spending more money wouldn’t increase achievement, wouldn’t spending less money have no effect on achievement either? “Brilliant!” I thought.
The time came for the cross-examination, and, among many other questions, the plaintiffs’ attorney asked this question.
“That—that almost follows,” Hanushek replied.
It wasn’t the Perry Mason moment I was hoping for, but it was enlightening nevertheless. The reality is that Hanushek’s claim that money doesn’t matter was based on natural variations among districts in their spending patterns, and wealthy districts spent more and had better educational outcomes than poorer districts that spent less. There were no studies showing what would happen if spending were to increase or decrease precipitously over time ….
Dr. Hanushek’s analysis that there is not much relationship in Colorado between spending and achievement contradicts testimony and documentary evidence from dozens of well-respected educators in the State, defies logic, and is statistically flawed.[Ouch!]
For decades, judges at many levels in the judicial system have been cowered by complicated looking statistical testimony. One hopes that those days may be coming to an end.
Hanushek, Eric. (1997) Assessing the effects of school resources on student performance: An update. Educational Evaluation and Policy Analysis 19 (2), 141-164.
Glass, Gene V. (2002). Teacher characteristics. Chapter 8 (Pp. 155-174) in Molnar, Alex. (Ed.) School Reform Proposals: The Research Evidence. Greenwich, CT: Information Age Publishing, Inc.
Gene V Glass
University of Colorado Boulder
Arizona State University