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Let's All Beware the Latin Square

Summary: [This abstract is based on the author's abstract.]

Great caution must be used when applying the three-level Latin square (L9 orthogonal array) experimental design for more than two factors. Statistical two-factor interactions seriously bias the averages determined at each factor level. A complete numerical example using industrial data is given. Additional three-level fractional factorials with similar characteristics are the L18, L27, and L36 designs. It is difficult to predict a statistical two-factor interaction in advance because it is an artifact of a surrogate model. Alternative second-order experimental designs are suggested.

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  • Topics: Design of Experiments
  • Keywords: Interactions, Fractional factorial design, Factorial experiments, Design, Orthogonal array (OA)
  • Author: Hunter, J. Stuart
  • Journal: Quality Engineering