ENBIS: European Network for Business and Industrial Statistics

Graphical aids in the analysis of non-regular two-level designs

Abstract

Submitted by

John Tyssedal

Authors

John Tyssedal and Ranveig Niemi

Affiliation

Norwegian University of Science and Technology

Abstract

While normal and half-normal plots together with Lenth’s method are used extensively in the analysis of regular two-level design and their fractions, these methods may be of little help in the analysis of non-regular two-level designs like Plackett-Burman designs for instance. The reason why is that the aliasing between main effects and higher order effects is rather complex. However, when only a few higher order interactions are active, many non-regular designs have a very structured alias pattern. In this talk we demonstrate how scatter-plots, cluster analysis and a method based on orthogonalized scatter-plots may give valuable information about active effects and also be supportive for other analysis methods for these designs.

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