Top panel: marginalized likelihood distribution for the slope parameter, α, of the linear fit to the full α.btfr sample. The vertical solid and dotted marks denote the maximum likelihood value and 1σ range, α = 3.74 ± 0.11. Bottom panel: same as the top panel but for the intercept parameter, β. The maximum likelihood value and 1σ range for the parameter is β = 9.500 ± 0.013, and refers to the pivot value .