cond.index: Calculation of Condition Indices for Linear Regression

Description Usage Arguments Details Value Author(s) References See Also Examples

View source: R/cond.index.R

Description

Diagnosis of collinearity in X

Usage

1

Arguments

formula

formula of the form ‘groups ~ x1 + x2 + ...

data

data frame (or matrix) containing the explanatory variables

...

further arguments to be passed to lm

Details

Collinearities can inflate the variance of the estimated regression coefficients and numerical stability. The condition indices are calculated by the eigenvalues of the crossproduct matrix of the scaled but uncentered explanatory variables. Indices > 30 may indicate collinearity.

Value

A vector of the condition indices.

Author(s)

Andrea Preusser, Karsten Luebke ([email protected])

References

Belsley, D. , Kuh, E. and Welsch, R. E. (1979), Regression Diagnostics: Identifying Influential Data and Sources of Collinearity, John Wiley (New York)

See Also

stepclass, manova

Examples

1
2
3
data(Boston)
condition_medv <- cond.index(medv ~ ., data = Boston)
condition_medv

Example output

Loading required package: MASS
 [1]  1.000000  2.516245  3.242633  3.905405  6.469852  7.785597  9.651169
 [8] 11.640227 15.580784 19.840440 27.662710 28.912366 37.417710 87.318288

klaR documentation built on May 31, 2017, 1:53 a.m.

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