CatReg Software for Categorical Regression Analysis (2006)
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CatReg is a computer program, written in the R (http://cran.r-project.org) programming language, to support the conduct of exposure-response analyses by toxicologists and health scientists. CatReg can be used to perform categorical regression analyses on toxicity data after effects have been assigned to ordinal severity categories (e.g., no effect, adverse effect, severe effect) and associated with up to two independent variables corresponding to the exposure conditions (e.g., concentration and duration) under which the effects occurred. CatReg calculates the probabilities of the different severity categories over the continuum of the variables describing exposure conditions. The categorization of observed responses allows expression of dichotomous, continuous, and descriptive data in terms of effect severity and supports the analysis of data from single studies or a combination of similar studies.
The special features offered by CatReg include options for:
- stratifying the analysis by user-specified covariates (e.g., species, sex, etc.)
- choosing among several basic forms of the exposure-response curve;
- using effects assigned to a range of severity categories, rather than a single category;
- using cluster-correlated data;
- including user-specified weights;
- using aggregate data; and
- query-based exclusion of user-specified data (i.e., filtering) for sensitivity analysis.