How do you know that schools with effective organizations haven't simply benefited from teaching bright kids or receiving the support of educated parents? In other words, how do you know that effective organizations promote student achievement rather than the other way around?

There are several reasons why we are confident that effective school organization means a great deal for student achievement. The first is that in our analysis of student achievement, school organization competes directly with many characteristics of student and family background to explain the observed changes in test scores. In this competition, school organization fares very well, coming in second. Now it is true that school organization may be receiving undue credit for influences on test scores that are really the result of student body influences working through the school organization. But it is also true that student bodies may be receiving undue credit – credit that should go to school organization – for boosting test scores. After all, it is school reputations for organization effectiveness that lead many parents to buy homes in the jurisdictions of better schools, and that, in turn, provide effective organizations with better students.

So, how should the alternative forms of "undue credit" be corrected'? Should the influence of school organization be downgraded because organization may be influenced by student body characteristics? Or should the influence of organization be upgraded because student body characteristics are influenced by school organization? The correct answer is that both should be done simultaneously. Unfortunately, such a correction is statistically impossible with our data. We must, therefore, be content that our estimate of the effect of organization on achievement strikes a happy medium between over- and under-estimation.

But there is another reason for confidence that school organization makes asubstantial independent difference for school performance. That is, we analyzed a variety of possible causes of school organization and found that the characteristics of students and parents were not the most important sources of effective or ineffective organization. A school may be effectively organized whether it is teaching bright students or educationally disadvantaged students, and whether it is supported by educated parents or scarcely supported by parents at all. As a result, a properly organized school can have a positive, independent effect on students of any kind.