Cluster randomized trials in health care may involve three instead of two levels, for instance, in trials where different interventions to improve quality of care are compared. In such trials, the ...

This is a preview. Log in through your library . Abstract On-going public health surveillance is essential to the detection and monitoring of epidemics. We present statistical methods for determining ...

Precedents set in the historic Barr case continue to raise questions over suitable sample-size criteria. "... the number of retests performed before a firm concludes that an unexplained out of ...