Top: distribution of the 1.4–3 GHz radio spectral indices. The distributions of the uncensored values and the lower limits (placed in the bins corresponding to those values) are shown separately by the blue and red histograms, respectively. In both cases, the histogram bin size is 0.1. The sample median, shown by the vertical dashed line, is (same for the full sample and a sample from which the three VLBA-detected sources were removed; Table 2). Bottom: distribution of the ν_obs = 3 GHz brightness temperatures, where the VLBA-detected sources with high T_B values are omitted for legibility purposes. Again, the uncensored values and the lower limits are plotted separately. The bin size is 3 K. The median values, T_B = 12.6 K for the full sample and T_B = 12.3 K for a sample from which the VLBA-detected sources were removed, are marked by the vertical dashed lines (the two lines are nearly indistinguishable owing to a minute, 0.3 K difference in the medians).