Abstract
Before experimental units are assigned to treatments, information may exist on the units that can be used to evaluate their uniformity. One objective in using this information is to allocate experimental units to treatments so that group means and group variance-covariances are as similar as possible, minimizing potential confounding effects on treatment responses. A procedure is proposed for constructing designs that have near homogeneity. One advantage of the approach is that no particular model need be specified at the time of allocation. Also, the procedure is invariant with respect to linear transformations and can identify outliers in the pretreatment data. An example is given of a vineyard study to assign sixteen plants to CO2 treatments in a photosynthesis study. A weighted procedure that incorporates sample sizes as weights for assignment is recommended for balanced designs.
- Received November 1979.
- Revision received February 1980.
- Accepted February 1980.
- Published online January 1980
- Copyright 1980 by the American Society for Enology and Viticulture
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