Calibrated GRB Hubble diagram (black filled diamond) up to very high values of redshift, as constructed by applying the local regression technique with the Reichart likelihood: we show overplotted the behavior of the theoretical distance modulus μ(z) = 25 + 5log d_L(z) corresponding to the favored fitted CPL model (red line), with w₀ = −0.29, w₁ = −0.12, h = 0.74, Ω_m = 0.24, and the standard ΛCDM model (gray line) with Ω_m = 0.33, and h = 0.74. They are defined by Eqs. (12) and (21). The blue filled points at lower redshift are the SNIa data.