lm2: Modified lm() to use a specified design matrix

In JWileymisc: Miscellaneous Utilities and Functions

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

See Also

lm

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)

JWileymisc documentation built on April 13, 2025, 9:07 a.m.