lm.ridge

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Ridge Regression

Fit a linear model by ridge regression.

Keywords
models
Usage
lm.ridge(formula, data, subset, na.action, lambda = 0, model = FALSE, x = FALSE, y = FALSE, contrasts = NULL, ...)
Arguments
formula
a formula expression as for regression models, of the form response ~ predictors. See the documentation of formula for other details. offset terms are allowed.
data
an optional data frame in which to interpret the variables occurring in formula.
subset
expression saying which subset of the rows of the data should be used in the fit. All observations are included by default.
na.action
a function to filter missing data.
lambda
A scalar or vector of ridge constants.
model
should the model frame be returned? Not implemented.
x
should the design matrix be returned? Not implemented.
y
should the response be returned? Not implemented.
contrasts
a list of contrasts to be used for some or all of factor terms in the formula. See the contrasts.arg of model.matrix.default.
...
additional arguments to lm.fit.
Details

If an intercept is present in the model, its coefficient is not penalized. (If you want to penalize an intercept, put in your own constant term and remove the intercept.)

Value

A list with components
coef
matrix of coefficients, one row for each value of lambda. Note that these are not on the original scale and are for use by the coef method.
scales
scalings used on the X matrix.
Inter
was intercept included?
lambda
vector of lambda values
ym
mean of y
xm
column means of x matrix
GCV
vector of GCV values
kHKB
HKB estimate of the ridge constant.
kLW
L-W estimate of the ridge constant.

References

Brown, P. J. (1994) Measurement, Regression and Calibration Oxford.

lm

Aliases
• lm.ridge
• plot.ridgelm
• print.ridgelm
• select
• select.ridgelm
Examples
library(MASS) longley # not the same as the S-PLUS dataset names(longley)[1] <- "y" lm.ridge(y ~ ., longley) plot(lm.ridge(y ~ ., longley, lambda = seq(0,0.1,0.001))) select(lm.ridge(y ~ ., longley, lambda = seq(0,0.1,0.0001))) 
Documentation reproduced from package MASS, version 7.3-45, License: GPL-2 | GPL-3

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