**Use appropriate tools**

to fit and predict the two-way models.

**For PARAFAC regression**

fit a PARAFAC model to the calibration data and regress the dependent variable onto these scores. Calculate the scores of the validation data from the loadings of the PARAFAC model and use the regression coefficients for predicting the color.

**Decide on **

how/whether to center the spectral data prior to PARAFAC modeling and/or prior to regression.

**Note that**

since the PARAFAC model is not nested, each PARAFAC model has to be fitted separately.