PLS Prediction Cross Validation

PLS prediction can be performed in analogy to PCR by PCR PLS pred. m (p.302) already introduced earlier. For this, we need to determine the prognostic vector, vpTog. Using the results of the PLS calibration, it can be computed as  

During cross validation, it is most convenient to compute this prognostic vector as a function of the number of factors. This results in a collection of prognostic vectors, conveniently stored in a matrix V prog. After determination of the optimal number of factors, the appropriate column can be selected as prognostic vector. The predicted quality qs for an unknown sample with the spectrum ys is then calculated as  

For PCR and PLS, the principle of cross validation is identical. We refer to Cross Validation (p.303). The following function PLS cross.m differs from PCR cross only in the few lines performing the calibration and calculating the prognostic vector. 

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