Reduced chi-square values, , vs. halo mass associated with the best-fitting NFW profiles computed considering the noise-free source sample by fitting the concentration parameter (dashed green line) and using the relation reported by Duffy et al. (2008) to fit the profile (dashed orange line) and for profiles derived considering the noisy source sample (dashed purple line). The gray region correspond to χ² values from 0.5 to 1.5.