Jay Greene’s analysis of a new Journal of Public Economics study of spending and student performance is a must-read.  Professor Greene writes,

Some researchers and journalists have become very excited about a new set of studies that claim to find a causal relationship between increasing school spending and improving student outcomes.  These folks acknowledge that the vast majority of earlier research found no relationship between additional resources and stronger results, but that research was purely observational.  Perhaps school systems with weaker outcomes tend to get a larger share of increased spending, creating the false impression that more money doesn’t help.  That is, perhaps bad outcomes often cause more money, not the other way around.

There is a new wave of research that claims to find the causal relationship between school spending and student outcomes and those new results are much more positive.  The problem is that the new research pretty clearly falls short of having strong causal research designs.  Instead, the new research just seems to be substituting different non-causal methods with a different potential direction of bias for the old ones.

Greene’s discussion can be technical at times.  In essence, he argues that these studies lack the research components needed to approximate randomness (and thus indicate causality).