This is very much the field of Econometrics, perhaps the subset of Mathematics with the weakest theoretical footing. The short answer is not 100% because you c

This is very much the field of Econometrics, perhaps the subset of Mathematics with the weakest theoretical footing. The short answer is not 100% because you can never 100% prove there isn't some other bigger cause that you just don't see. [1] Once you accept that, there are ways to test theories on the data (requires some knowledge of the subject matter) to piece it out. In this case, you're not going to get an absolute law of science, but you might get a clue for a policy decision. James Heckman [0] is one of several who make this their life's work. He has applied this analysis to fields like early childhood education. [0] http://www.nber.org/papers/w13934 http://www.nber.org/papers/w13934 [1] http://en.wikibooks.org/wiki/Econometric_Theory/Regression_versus_Causation_and_Correlation http://en.wikibooks.org/wiki/Econometric_Theory/Regression_v...