Fig. 4
Left plot Interval PLS-DA (iPLS-DA) plot of classification of the 4 diet groups (LP/LGI, LP/HGI, HP/LGI and HP/HGI) from 23 averaged 1H NMR spectra of urine calculated on 108 intervals (full CV) showing the number of misclassification in absolute numbers together with the number of LV’s. The dashed red horizontal line indicates the number of misclassification for the full spectral model using 2 LV’s, and the solid red line is the average NMR spectrum. The small insert shows the 23 average signals from the metabolite around 8.46 ppm, which is linked to the metabolite formate. Right plot The actual versus predicted plot shows almost perfect separation of the HGI diets versus LGI diets using the selected interval. The RMSECV of the global model calculated with 3 LV′s is markedly improved for the interval in red (8.43–8.49 ppm). The solid line is reference for full agreement, whereas the dotted line is the best-fitting linear regression line