2–10 keV luminosities of X-ray AGNs (small black points) and X-ray detected QSOs (large red open points) over redshift, based on photometry from the XMM-COSMOS survey (Brusa et al. 2010). The mean X-ray luminosity (in log units) of QSOs in our nominal redshift bins are plotted as large black square points, with the error bars showing the median absolute deviation of the data points from the mean. QSOs are typically more luminous than most X-ray AGNs at low redshifts, but span a similar range in X-ray luminosities as XMM-COSMOS AGNs at z > 1. Despite this, there is an increase in the mean X-ray luminosity with redshift for the QSOs in our sample.