Example of screening process using Mahalanobis distance. Mahalanobis distance outlier screening of a single batch (370 leaf samples) of the rice mutant population. (a) A single iteration of the Mahalanobis distance analysis for batch 0800-0850 based on one randomly chosen reference sample (sample 0810-4). The rest of the samples (x-axis) were sorted in descending order of their distance (y-axis) compared to the reference sample. (b) Summary of outliers based on five iterations of Mahalanobis distance calculations using randomly selected reference sets from the same batch.