Effect of inclination on the luminosity function shape, and how this effect depends on the slope values of the luminosity function. Left: observed luminosity function n(L), in blue dashed, as per the Ross et al. (2013) parametrisation: the luminosity function is a broken power law with indexes α = −1.34 and β = −3.56, and log(ϕ_*) = − 6.15. A Pure Luminosity Evolution is assumed. In this figure we show, as an example, the results for z = 1. In solid red, the intrinsic luminosity function m(ℒ), which is corrected for inclination effects. Right: same as the left panel, but with an observed luminosity function assumed to have indexes α = −0.8 and β = −4.5. The comparison between the two panels shows that a greater difference between α and β accentuates the knee distortion and the variance between m(ℒ) and n(L) at higher luminosities. For a better comparison, the red solid line of the left panel is also plotted in the right panel, in grey.