*2.3. Removing Selection Bias and Redshift Evolution*

After defining the limiting lines, we can then mimic the evolution of this variable with redshift using a simpler function of redshift, *f*(*z*) = <sup>1</sup> (1+*z*) *δ* . We here adopt the choice of a simple function, but in principle it is possible to use a more complex function as already shown in [77] and obtain compatible results. Using a modified version of Kendall's *τ* statistics, we can compute an evolutionary function *f*(*z*) where the slope of the function is defined by *δ*. The values for *δ* where *τ* = 0 represent the removal of evolutionary effects. We define errors on *δ* out to 1 *σ*, corresponding to the *δ* values where *τ* = ±1.
