Australian & New Zealand Journal of Statistics

Multiphase experiments with at least one later laboratory phase. II. Non orthogonal designs

Journal Article

Many experiments involve two or more phases, with the second phase often being a laboratory phase. This paper adds principles and laws for designing nonorthogonal experimental designs to those given by Brien et al. (2011) for orthogonal experimental designs. It emphasizes the ramifications of having the same numbers of units in the two phases and advocates for an orthogonal second‐phase design, if possible. Four mechanisms for achieving orthogonal second‐phase designs are described. How to formulate mixed models based on the factor allocation employed in the design is explained and illustrated. The use of the R packages dae and od for producing and assessing the properties of two‐phase designs is detailed and scripts are provided in the Supplementary materials.

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