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

Diagnosis of collinearity in X

1 | ```
cond.index(formula, data, ...)
``` |

`formula` |
formula of the form ‘ |

`data` |
data frame (or matrix) containing the explanatory variables |

`...` |
further arguments to be passed to |

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.

A vector of the condition indices.

Andrea Preusser, Karsten Luebke ([email protected])

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

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

```
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
```

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