On Generalized Linear Model Method for Detecting Dispersion Effects in Unreplicated Factorial Designs

There are numerous approaches to screen location effects for unreplicated experiments, but only a handful to screen dispersion effects. Generalized linear models, popular in analyses of non-normal data, were recently proposed to screen both location and dispersion effects simultaneously. This paper illustrates and explains the impact of unidentified location effects on dispersion effects identification for such procedures. A remedy is proposed to recover the loss of power of the GLM method due to such impact.

Keywords:

• Heterogeneous Variance Models
• Quality Improvement
• Two-level Fractional Designs
• Variance Reduction