Sometimes it's nice when good research does no more than confirm what conventional wisdom tells us all along. I think that's the case with a just-released study from the National Bureau of Economic Research called "Estimating the Effect of Leaders on Public Sector Productivity: The Case of School Principals."
The researchers used public school data from Texas -- which allowed them to study a large sample of 7,420 principals work from 1995-2001 for 28,147 yearly looks at principals -- to determine if the quality of principal leadership in fact did make a difference in student performance.
The answer -- as one would hope and probably expect -- is, yes, it does. The one twist is that it makes much more of a difference -- read that as positive impact -- in schools with higher poverty rates than it does in schools where students are more advantaged.
The study incorporated many measures and strategies to isolate the principal's impact on student performance from other factors that principals can't control. The main outcome measure used was students' standardized test scores and the quality of principal was judged by data showing personnel management traits. For instance, a good principal was one whose low performing school experienced a higher rate of teacher turn over, as long as more effective teachers were being hired to replace less effective ones, or whose high performing school had little teacher turn over, thus retaining top educators.
The study is available for download for $5 (or for free to certain groups such as journalists and government workers) at the National Bureau of Economic Research.