Robert J. Boik

Learn More
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)
Estimates of a population’s growth rate and process variance from time-series data are often used to calculate risk metrics such as the probability of quasi-extinction, but temporal correlations in the data from sampling error, intrinsic population factors, or environmental conditions can bias process variance estimators and detrimentally affect risk(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)
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)
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)
Clinical researchers have noted that compared with other diagnostic groups, adults with Borderline Personality Disorder tend to demonstrate relatively more thought disorder on unstructured projective tests (e.g., Rorschach) than on structured objective tests of cognitive performance (e.g., Wechsler Adult Intelligence Scale; WAIS). Using archival data, our(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)