Description Usage Arguments Details Value Author(s) References Examples

The function calculates the brant test by Brant (1990) <doi: 10.2307/2532457> for ordinal logit models to test the parallel regression assumption.

1 | ```
brant(model,by.var=F)
``` |

`model` |
the polr-Object generated with polr() |

`by.var` |
OPTIONAL if set to true, the tests are made for each variable instead of each coefficient. Default: FALSE. |

The function calculates the brant test for parallel regression assumption. The brant test was published by Brant (1990). The function works with models generated with the function polr() from the package 'MASS'.

The output is the brant test, which shows if the parallel assumption holds or not.

Benjamin Schlegel, kontakt@benjaminschlegel.ch

Brant, R. (1990) Assessing proportionality in the proportional odds model for ordinal logistic regression. *Biometrics*, **46**, 1171–1178.

1 2 3 4 5 |

```
Call:
MASS::polr(formula = Smoke ~ Sex + Height, data = data, Hess = TRUE)
Coefficients:
Value Std. Error t value
SexMale 0.09478 0.4808 0.1971
Height 0.02785 0.0243 1.1458
Intercepts:
Value Std. Error t value
Never|Occas 6.3113 4.0564 1.5559
Occas|Regul 6.9224 4.0619 1.7042
Regul|Heavy 7.8802 4.0732 1.9347
Residual Deviance: 287.0276
AIC: 297.0276
(29 observations deleted due to missingness)
--------------------------------------------
Test for X2 df probability
--------------------------------------------
Omnibus 3.28 4 0.51
SexMale 1.58 2 0.45
Height 0.02 2 0.99
--------------------------------------------
H0: Parallel Regression Assumption holds
```

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