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arXiv · 1804.00545

A Formula for Type III Sums of Squares

Lynn Roy LaMotte
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Abstract

Type III methods were introduced by SAS to address difficulties in dummy-variable models for effects of multiple factors and covariates. They are widely used in practice; they are the default method in several statistical computing packages. Type III sums of squares (SSs) are defined by a set of instructions; an explicit mathematical formulation does not seem to exist. An explicit formulation is derived in this paper. It is used to illustrate Type III SSs and their properties in the two-factor ANOVA model.

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Lynn Roy LaMotte. 2018-03-29. A Formula for Type III Sums of Squares. https://arxiv.org/abs/1804.00545

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