Fig 1. Representation of all elements of the experimental design.

The tensor for the complete design consisted of four dimensions: the experimental cases (total 24 –the shaded areas in the figure are for cases 1 and 24), time points (6, hourly), interventions (4, including the vehicle only) and spectral bins (344, following data pretreatment). The total number of 198 144 data points (= 24 x 6 x 4 x 344) thus required bioinformatics analysis to uncover the information from the four interventions. All 24 experimental subjects agreed to participate in each of the four interventions (i.e. a cross-over design), indicated by 1 (vehicle only), 2, 3 and 4. For each of the 24 cases, urine samples (from which the NMR spectral bins were generated) were collected at one hour prior to the intervention (time –1), just before the intervention (time 0) and then at hourly intervals for 4 hours (times 1–4). The results reported in this paper apply to only one of the treatments (consumption of flavored water), which yielded 49 536 data points.