Some authors recommend the use of an additional test for detecting increases in the spread, when using a control chart for individual observations. We examine this recommendation both in a practical situation and theoretically. Both studies show that the additional test gives somewhat more power...

Vector AutoRegressive (VAR) models have become popular in analyzing the behavior of competitive marketing systems. However, an important drawback of VAR models is that the number of parameters to be estimated can become very large. This may cause estimation problems, due to a lack of degrees of...

In 2005, a Dutch health insurer introduced a financial incentive directed to general practitioners to promote rational prescribing of statins and proton pump inhibitors (PPIs). Concomitantly, a regional institution that develops pharmacotherapeutic guidelines implemented two educational...