R: Modified lm() to use a specified design matrix

lm2 {JWileymisc}

R Documentation

Modified lm() to use a specified design matrix

Description

This function is a minor modification of the lm() function to allow the use of a pre-specified design matrix. It is not intended for public use but only to support modelTest.lm.

Usage

lm2(
  formula,
  data,
  subset,
  weights,
  na.action,
  model = TRUE,
  x = FALSE,
  y = FALSE,
  qr = TRUE,
  singular.ok = TRUE,
  contrasts = NULL,
  offset,
  designMatrix,
  yObserved,
  ...
)

Arguments

`formula`	An object of class "formula" although it is only minimally used
`data`	the dataset
`subset`	subset
`weights`	any weights
`na.action`	Defaults to `na.omit`
`model`	defaults to `TRUE`
`x`	defaults to `FALSE`
`y`	defaults to `FALSE`
`qr`	defaults to `TRUE`
`singular.ok`	defaults to `TRUE`
`contrasts`	defaults to `NULL`
`offset`	missing by default
`designMatrix`	a model matrix / design matrix (all numeric, pre coded if applicable for discrete variables)
`yObserved`	the observed y values
`...`	additional arguments

Value

an lm class object

Examples

mtcars$cyl <- factor(mtcars$cyl)
m <- lm(mpg ~ hp * cyl, data = mtcars)

x <- model.matrix(m)
y <- mtcars$mpg
m2 <- JWileymisc:::lm2(mpg ~ 1 + cyl + hp:cyl, data = mtcars,
  designMatrix = x[, -2, drop = FALSE],
  yObserved = y)

anova(m, m2)

rm(m, m2, x, y)