Supplemental Figure 1. GALGO algorithm: an example of 10 samples each for treated and control. Adapted from GALGO tutorial (Figure 10 and 22, version February 2006; http://biptemp.bham.ac.uk/vivo/galgo/Tutorial.pdf). 1number of splits = min(150, sample size) = 20; split ratio determined by “train” = 0.67 and “test” = 0.33; 2number of splits classification.train.Ksets = max(min(round(13 - 20/11), 20), 3) = 11; classification.train.splitFactor=2/3.

Samples of a chemical-tissue condition

10 treated + 10 control

Training7 + 7

Test3 + 3

Training5 + 5

Test2 + 2

GA process

Bootstrap random split 20 times1

Random split 11 times2