1. A spectroscopic method for monitoring heterogeneity of a sample, comprising: acquiring a plurality of sampled spectroscopic measurements distributed over a range of different micro locations in a macro-sample of the sample, repeating the step of acquiring for each of a plurality of micro-locations in each of further macro-samples of the sample, and deriving from the sampled spectroscopic measurements acquired in the steps of acquiring a statistical measure of chemical heterogeneity.