Cover: Using the PISE Criterion to Measure the Effects of Imbalance in the Analysis of Covariance

Using the PISE Criterion to Measure the Effects of Imbalance in the Analysis of Covariance

Published 1983

by S. James Press


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Describes a new statistical technique for comparing unbalanced experimental designs which will be modeled by the univariate analysis of covariance. The author proposes minimizing a design criterion variable called PISE (percent inflation of the standard error of a contrast). The research was motivated by the need to design an experiment to measure the effectiveness of a potential new Army recruitment policy. The policy would provide greater management flexibility in paying cash bonuses to eligible "high-quality" young men who agree to enlist in the U.S. Army. Results are provided for both the standard Gauss-Markov model (constant error variance) and the model with heteroscedasticity. Also discussed is the problem of attributing the increased variance caused by imbalance in a design to particular covariates. When implemented, the proposed PISE criterion will generate a design which has greater sensitivity to treatment effect differences.

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