mosaic (version 0.13.0)

mm: Construct a model based on groupwise means

Description

Calculate groupwise means, presenting the result as a model in the style of lm.

Usage

mm(formula, data = parent.frame(), fun = mean, drop = TRUE, ...)

Arguments

formula

A formula. The left-hand side specifies the variable over which the mean will be taken. The right-hand side gives the grouping variables, separated by &.

data

A data frame to which the formula variables refer. If not specified, variables will be taken from the current environment.

fun

The function used to calculate the means. Default: mean.

drop

Logical flag indicating whether to drop unoccupied groups. Default TRUE. NOT YET IMPLEMENTED.

...

Additional arguments to be passed to the fun doing the calculation.

Value

• mm returns an object of class groupwiseModel. The functions fitted.values, residuals, coefficients, and summary are useful for extracting various features of the value returned by mm

Details

mm is a sort of training function for lm, meant to provide a basis for discussing inference and introducing resampling in a simple, intuitive setting of groupwise means. lm provides a better, more general facility. When using lm to recreate the results of mm, include all the interaction terms, that is, use * instead of &. See the examples.

See Also

lm, do