If anything, it seems that the presence of teacher contracts in a state has a rather large, positive effect on achievement.
Now, some may object to this conclusion. They might argue that I can’t possibly say that teacher contracts alone caused the higher scores in these states. That there are dozens of other factors besides contracts that influence achievement, such as lack of resources, income, parents’ education, and curriculum, and that these factors are at least partially responsible for the lower scores in the ten non-contract states.
My response: Exactly.