Figure 3.

An overview of the testing/training. An overview of the testing/training procedure used in this study. The rectangles illustrate the predictor matrix. At level 1 we split the data into a test set and a training set (25/75). This was repeated 10 times. Inside our suggested method, the stepwise elimination, there are two levels of cross-validation. First a 10-fold cross-validation was used to optimize selection parameters fand d. Second, a leave-one-out cross-validation was used to optimize the L-PLS parameters, such as αand the number of components.