# Calculates lambda for Box-Cox power transformation

### Description

Calcluates and plots log-liklihoods lambda for power transformation of response variable. Reports chi-square test of lambda <> 1. All values of Y must > 0 or function will crash. Add offset to Y if necessary (see example). Default lambda range is -2 to 2. Uses boxCox() from car package.

### Usage

1 | ```
modelBoxCox(Model, Lambdas = seq(-2, 2, by = 0.1))
``` |

### Arguments

`Model` |
an unweighted linear model, produced by |

`Lambdas` |
a vector of lambda values to plot. Default is seq(-2,2,by=0.1) |

### Author(s)

John J. Curtin jjcurtin@wisc.edu

### References

Box, G. E. P. & Cox, D. R. (1964). An analysis of transformations (with discussion). Journal of the Royal Statistical Society, 26, 211-252.

### See Also

boxCox(), boxcox()

### Examples

1 2 | ```
m = lm(interlocks + 1 ~ assets+nation, data=Ornstein)
modelBoxCox(m)
``` |