Uncertainty distribution, Δz/(1 + z), for the 170 BLAGN/QSOs in our sample considering the MEL approach. Non-outlier and outliers are represented by filled and open histograms, respectively. The continuous line represents the best Gaussian fit to the observed distribution of non-outliers. The number of non-outliers (#), the center, and σ of the best-fit Gaussian distribution are indicated.