Scatter of absolute magnitudes calculated for repeated observations of the same object as a function of absolute J magnitude. Thick lines show running median errors for calculations using YY a), Dartmouth b) and Padova isochrones c). The Boxcar for the running median is  ± 0.5 mag. The shaded area shows the 20 to 80 percentile range of the error distribution and the dashed line traces the number of repeated objects per 0.1 mag wide absolute magnitude bin.