Tim Schofield

Tim Schofield is senior director, nonclinical statistics, at Merck Research Laboratories.

Larger and strategic sampling and testing plans can improve process understanding and characterization.

In his Feb. 2005 viewpoint article, "In Defense of Singlet Testing," Torbeck (1) draws an important philosophical distinction between "standards" and "specifications." He argues that specifications are criteria selected by manufacturers for statistical control of their products, whereas compendial standards are absolute requirements. This distinction is entirely compatible with modern concepts of statistical process control.