Analysis of variance; comparing models



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Analysis of variance; comparing models

The model fitting function aov(formula, data=data.frame) operates at the simplest level in a very similar way to the function lm(), and most of the generic functions listed in Table 2 apply.

It should be noted that in addition aov() allows an analysis of models with multiple error strata such as split plot experiments, or balanced incomplete block designs with recovery of inter-block information envisaged. Model formula

response i<>mean.formula + Error(strata.formula)

Specifies a multi-stratum experiment with error strata defined by the strata.formula. In the simplest case, strata.formula is simply a factor, when it defines a two strata experiment, namely between and within the levels of the factor.

For example, with all determining variables factors a model formula such as that in:

fm <- aov(yield v + n*p*k + Error(farms/blocks), data=farm.data)

would typically be used to describe an experiment with mean model v + n*p*k and three error strata, namely ``between farms'', ``within farms, between blocks'' and ``within blocks''.





Erik Moledor
Tue Jan 31 21:02:18 EST 1995