(Reliability of league tables of in vitro fertilisation clinics: retrospective analysis of live birth rates)
League tables of schools and hospitals are increasingly common and much attention is paid to the precise position of an institution in the table. In this week's BMJ, Marshall and Spiegelhalter describe a new statistical technique that can be used to quantify the uncertainty about ranking. They have applied it to in vitro fertilisation clinics in the UK and found that the rankings were not entirely meaningful and therefore it would be unwise to take them too seriously. Positions in ranking can alter radically year on year, but this does not necessarity mean that a significant change in the success rate has occured.
Dr David Spiegelhalter, Senior Statistician, MRC Biostatics Unit, Institute of Public Health, Cambridge firstname.lastname@example.org