A formula for Type III sums of squares

  title={A formula for Type III sums of squares},
  author={Lynn Roy Lamotte},
  journal={Communications in Statistics - Theory and Methods},
  • L. Lamotte
  • Published 29 March 2018
  • Mathematics
  • Communications in Statistics - Theory and Methods
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… 
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