Relation between log L_IR and log L_agn with S/N_W3 & W4 > 5. The blue and orange circles indicate low-z quasars, whereas the green and red diamonds indicate high-z sources. The orange circles and red diamonds indicate low-z and high-z quasars with Spitzer M24 data. In panel a the blue line denotes the best-fit Bayesian regression for the low-high-z data with S/N_W3 & W4 > 5, the orange line is the Bayesian regression for the low-high-zSpitzer data from both low-z and high-z, and the green and red dashed lines represent the best Bayesian fit with the low-z sample weighted and low-z with Spitzer weighted, respectively; the black line gives the 1:1 scaling relation between L_IR and L_agn. In panel b the big black circles represent the medians calculated for the 0.5 dex in log L_agn for both redshift samples (low-high-z) and the orange big triangles stand for the medians calculated for both redshift samples with the Spitzer data (low-high-zSpitzer). For the black and the magenta points, the error bars represent MAD. The exact values of the fitted parameters are listed in Table 1.