Fig. 1

Compositional data from short-term round-robin set (RR) plotted by analyst. Each batch was run by a different analyst with 7–10 replicates of the NIST RM 8491 material. This material was extracted in bulk, and all the data were collected from one chromatography system in order to minimize variability. The gray band in the background shows the two times the grand standard deviation centered on the grand average (denoted by the central line) for the entire RR dataset. Analysts 5 and 9 did not run this experiment. The carbohydrate data for analyst 4 was an outlier and not included here, therefore a total component closure cannot be calculated