Quasars and Cosmological Evolution

The first evidence that quasars exhibit a non-uniform distribution in the universe was obtained ten years ago from a sample of 33 quasars in the 3CR catalogue. Much larger samples of radio quasars are now available and we will discuss the results in terms of an exponential decrease of quasar numbers with cosmic time. Only a few samples of optically selected quasars exist. We will show that their counts indicate a non-uniform space distribution, even if the redshifts are non-cosmological.