The Minneapolis Star-Tribune completed a comprehensive statistical analysis of school spending and test scores in Minnesota. The results found no connection between per-pupil funding and student achievement on test scores. The poverty level of the students was a much more accurate predictor of test scores than per-pupil funding.
However, the federal free lunch program was used to determine the number of students living in poverty. See my earlier post on problems with this indicator. The Star-Tribune analysis would change significantly if Minnesota has a free-lunch over-identification problem.