A Critical Assessment of Two-Stage Group Screening Through Industrial Experimentation

Abstract

Screening is the process of sifting through a set of factors through experimentation to determine the few important factors that have a substantial effect on a response. When the set of factors is large and interactions are anticipated, screening methods using single fractional factorial designs may require too many observations to be feasible. The methodology of two-stage group screening has been suggested as an alternative. This article gives the first description of practical aspects involved in running a two-stage group screening experiment for investigating interactions. Issues involved in the design and analysis of such an experiment are discussed in the context of a study run at Jaguar Cars on cold start optimization. The analysis of this experiment provides insight into how group screening works in practice and how the factorial effects of the individual factors relate to those of the grouped factors. Elicitation of information from subject specialists, choice of factor groups, and selection of designs for two-stage group screening are discussed. Through the analysis of the experimental data, it is shown that the process of group screening can provide an efficient method of detecting interactions among large numbers of factors.