[CraigS]

Originally Posted by renormalised

I'll actually have to read the paper myself before I comment on the specifics, but the fact that they have such a reduced dataset and have essentially ignored the correlations is an important point to bring up here.

These correlations are important in determining just what type of mechanism is controlling the emissions from the quasars and how it related to quasar age, distance etc. Without those correlations, you can't really make head nor tail of what is occurring, all you can do is speculate on how luminosity and redshift are related and what mechanism is possibly driving the luminosity and variability in the quasars. That's why you need to read the other papers that he cites from, including those earlier one of his own. You can only draw some basic conclusions from this paper, but only about this paper. Whilst many of the other studies have been done with even fewer quasars and quite a few others have been done with a lot more, arbitrarily excluding the correlation (or anti-correlation data as the case may be) data is not sound. He may have done a thorough analysis, but you have to look at it in the light of other results. It will be good to see what others make of his results and to see what they decide to publish.

Yep. Agreed.
Cheers