EDITOR—Marshall and Spiegelhalter have done a valuable service in questioning the reliability of the Human Fertilisation and Embryology Authority's league tables of in vitro fertilisation clinics.1 Unfortunately, the tables are probably even less reliable than these authors suggest.

The authority reports adjusted life birth rates, which are based mostly on the female patient's age. As the method of adjustment is unpublished one cannot judge whether the various factors are weighted correctly. Moreover, this adjustment does not embody all factors affecting outcome. These …