Average values of beaming parameter for different subsamples of the SDSS B-types. Left: mean values. Right: median values. The number ν represents the minimum number of points both in W3 and W4 bands required for an object to be part of the sample (see text). Averages corresponding to parameters computed from data with quality flags A, B, or C are plotted in red; the more restrictive case that only allows quality flag A are in blue.