Fig. 1

Area under the receiver operating characteristic curves. This was obtained by LOOCV of a 5-nearest-neighbor classifier over 1000 random selections of 50% of the arrays, using the HAGS probe sets (.sig suffix) and a new random selection of 150 probe sets each time (.rand suffix), over the two AD cohorts. AD Alzheimer’s disease, AUC area under the receiver operating characteristic curve, HAGS healthy ageing gene signature, LOOCV leave-one-out cross validation