The independent statistician for data monitoring committees.

Clinical trials are an essential part of the clinical research process. Recently, independent Data Monitoring Committees (DMCs) have been widely implemented to provide scientific and ethical oversight of pivotal clinical trials having irreversible outcomes such as death, stroke, disease recurrence or a serious adverse event. To carry out their responsibility, the DMC reviews interim analyses of accumulating data. We address the motivation for having the preparation and presentation of these interim analyses be conducted by an independent statistician who is not a member of the DMC and who is not the trial's lead or steering committee statistician. These views are based on having served as members of many DMCs as well as having been the independent statistician for several trials. Copyright 2004 John Wiley & Sons, Ltd.