In one general aspect, a spectroscopic method for monitoring heterogeneity of a sample is disclosed. In this method, sampled spectroscopic measurements are acquired over a range of different micro locations in a macro-sample of the sample. This step is repeated for micro-locations in further macro-samples of the sample, and a statistical measure of chemical heterogeneity is derived from the acquisitions. In another general aspect, differently sized samples are acquired, and a statistical measure of chemical heterogeneity is derived from these acquisitions.