Figure shows the histogram of the standard errors of fit (sE). By comparison to Fig. , it is seen that the overall fit errors are smaller. The average sE for the original fits was 0.100; after outlier rejection the average was 0.0867. Note that the threshold for outlier rejection is somewhat arbitrary; we could have been more aggressive in rejecting outliers, and the standard errors would of course be smaller, but we felt that threshold selected here was a good compromise. Once these outliers were rejected, we examined the range of organic compositions over which the data were fit, which indicates the valid range to be able to predict reliable retention factors. A histogram of these ranges for the 315 cases fit is shown in Fig. ; the average valid range was 40.7 %. This range is reduced somewhat from the original average range for all of the data, which was 41.2 %.