Likelihood contours for the intrinsic spectral index distribution parameters of sample 1 (solid line). The maximum likelihood parameters are denoted by cross signs. The square and triangle symbols denote the locations of the maximum likelihood parameters for samples 2 and 3, respectively. As a comparison, the likelihood contours for the sample of confidently identified blazars (as in Mattox et al. 2001) are overplotted with the dashed lines.