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The authors conducted a 30-year review (1969-1998) of the size of moderating effects of categorical variables as assessed using multiple regression. The median observed effect size (f(2)) is only .002, but 72% of the moderator tests reviewed had power of .80 or greater to detect a targeted effect conventionally defined as small. Results suggest the need to(More)
Cancer drugs are commonly administered in the clinic in the form of mixtures, also called cocktails or combinations. Assessment of synergistic and antagonistic interactions between drugs is therefore an important aspect of cancer research. Numerous methods have been proposed to assess drug interactions, each one based on a null (or additive) model. In this(More)
The construction and validation of a residence-based index of the degree of rurality are reported. The MSU Rurality Index is a locally normal index and assigns a quantitative measure of rurality to each participant in a study. Data required to compute the index are minimal; only two variables need be measured. Statistical analysis effort required to compute(More)
The purposes of this study were to describe the prevalence and correlates of alcohol use and to examine the ability to predict alcohol use among rural sixth- and seventh-grade children. The sample consisted of 625 children from six schools in small Montana towns. Self-administered questionnaires contained measures of sociodemographic characteristics,(More)
In a previous paper, Boik presented an empirical Bayes (EB) approach to the analysis of repeated measurements. The EB approach is a blend of the conventional univariate and multivariate approaches. Specifically, in the EB approach, the underlying covariance matrix is estimated by a weighted sum of the univariate and multivariate estimators. In addition to(More)
Inferences about fixed effects in mixed linear models are important in a variety of animal science studies. The statistical theory for making such inferences is well known, and if the variance components are known up to a proportionality constant, then optimal exact tests can be performed. Computing the test statistics, however, can still be problematic(More)
Eimeria bovis and Toxoplasma gondii differ in their susceptibility to macrophages activated by lymphokines. Interferon-gamma can activate macrophages to totally inhibit E. bovis sporozoite development, whereas growth of T. gondii tachyzoites in macrophages is not totally affected. The susceptibility of these parasites to oxygen intermediates and their(More)