Top: reconstruction of the Huble parameter using four PCs, obtained from the real sample, superimposed on direct Hubble parameter measurements reported by Stern et al. (2010) (green dots). Bottom: reconstruction of H(z) with four PCs and confidence intervals of 2σ obtained from the propagation of statistical uncertainties on Ω_m and w reported by Kessler et al. (2009), for MLCS2k2 results. In both panels, the blue dashed line represents H(z) in a flat XCDM cosmological model with w = −0.76 and Ω_m = 0.30 (best fit results reported by Kessler et al. 2009). Black curve corresponds to the best-fit reconstruction using 4 PCs and red lines are 2σ confidence levels.