(Color online) a) Likelihood distribution functions for De Filippis et al. (2005) sample. The solid and the dotted blue lines are likelihood functions for linear and non-linear parametrizations corresponding to the isothermal elliptical β model. The dashed and the dashed-dotted red lines are likelihood functions for linear and non-linear parametrizations corresponding to the isothermal spherical β model. b) The likelihood distribution functions for Bonamente et al. (2006) sample.