Sensory methods can be loosely separated into two groups: discriminant methods and descriptive methods. Simple models of difference tests rest on a number of assumptions, and not only are they not very good at showing that samples are the same, they are not good at detecting small differences. Quantitative Descriptive Analysis was developed from the Flavor Profile Method, and used an interval scale with emphasis on statistical evaluation of results. A variation of descriptive analysis is Free-Choice Profiling, where data are normally examined by generalized Procrustes analysis. Initial suspicion of the results has been overcome by more rigorous testing of their reliability. Time-intensity measurement is a special case of descriptive analysis, where a single characteristic is tracked as it changes over a period of time. Time-intensity has only relatively recently achieved wide application, and there have been rather few methodological studies.