ENBIS-8 in Athens

21 – 25 September 2008 Abstract submission: 14 March – 11 August 2008

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

22 September 2008, 15:40 – 16:00


Submitted by
John Tyssedal
John Tyssedal and Ranveig Niemi
Norwegian University of Science and Technology
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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