These results (Table 3) demonstrate that the choice of pre-treatment method(s) is crucial and may depend not only on the biological information to be acquired but also on the data analysis method to follow. For instance, a chemometric approach/method that focuses on (dis)similarities would differ from the PCA attempting to explain as much variation as possible in as few components as possible. Thus, varying data properties using data pre-treatment methods may, for instance, enhance the results of a clustering method, while obscuring the results of a PCA model .