Inaccurate data points are particularly troublesome in the analysis of unreplicated factorial experiments, but new techniques allow investigators to overcome this difficulty.

A cost model proposed by Box and Jenkins (1963) and later generalized by Box and Kramer (1992) for obtaining minimum cost for feedback control of processes is considered. Unfortunately, it is sometimes difficult to assign ...

Steepest ascent is an important tool for process improvement. This report discusses how to use the steepest ascent method in the context of constrained designs. The properties of the projection designs proposed in Report ...

It is well known that discrete feedback control schemes chosen to produce minimum mean square error at the output can require excessive manipulation of the compensating variable. Also very large reductions in the manipulation ...

Formulas are developed for assessing the probability and adequacy of rival models fitted to a common data set. Cases of full, partial and minimal variance information are treated. The use of the formula is demonstrated ...

How to pinpoint the most likely explanation for the results of unreplicated fractional factorial experiments.

The reasons for the need of an iterative approach to experimentation are explained. The consequent implications in the use of screening designs (fractional factorials and other orthogonal arrays), response surface designs ...

In this article, methods for demonstrating the iterative process of investigation are presented. As one example, it is shown how the sequential use of response surface techniques may be applied to devise an improved paper ...

Care is needed in interpreting results when regression analysis is applied to happenstance data. Although a fitted regression model may be useful for prediction of future values of a series, it may be totally misleading ...

The Six Sigma specification makes an allowance of 1.5 standard deviations for process drift. Simple ways in which a major part of such drift can be removed are given. These employ feedback adjustment methods specifically ...