This package provides functions for performing a univariate Analysis of Variance (ANOVA) to examine the differences between groups of means. The function
ANOVA can handle models with any number of fixed factors in a crossed design. It can handle both balanced and unbalanced data with or without missing elements. All results are given as type I sums of squares.
ANOVA also provides a number of post-hoc tests for comparisons.
The
data must be of the form
{{
1, 
1, ... y1}, {2, 2, ... y2}, ...} where
i,
i, and so on are the values of the categorical variables
vars associated with the
ith response,
yi.
The
vars argument is a list of symbols representing the categorical variables in the model.
The
model argument is a list of main effects and interactions that together specify the model. The interaction terms are given as the product of variables. For example, the full factorial model for a three-way analysis of variance can be written as
{, , 
, , , , }, where
, , are the main effects,
, , are the two-way interactions, and
is the three-way interaction. Models can also be written using
All to represent all main effects and interactions between the specified categorical variables. The full factorial model for a three-way analysis of variance can therefore also be written as
{, , , All}.
