Data are often encountered that fail the normality assumption, creating a dilemma between implementing the most appropriate analysis while maintaining appropriate inference. A recent extension of generalized linear models includes support for the Beta distribution, a flexible and accommodating distribution. SAS® can implement “Beta Regression ” through PROC NLMIXED, allowing the model’s likelihood to be specified in terms of its mean and a variance component, providing a flexible modeling tool and providing intuitive inference. We provide a brief theoretical introduction to Beta Regression as well as a macro that implements Beta Regression and provides residuals plots for model fit diagnostics
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