poTest {car}

Test for Proportional Odds in the Proportional-Odds Logistic-Regression Model

Description

The poTest function implements tests proposed by Brant (1990) for proportional odds for logistic models fit by the polr function in the MASS package.

Usage

poTest(model, ...)
## S3 method for class 'polr'
poTest(model, ...)
## S3 method for class 'poTest'
print(x, digits=3, ...)

Arguments

model

a proptional-odds logit model fit by polr.

x

an object produced by poTest.

digits

number of significant digits to print.

...

ignored.

Value

poTest returns an object meant to be printed showing the results of the tests.

Author(s)

John Fox [e-mail]

References

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

Examples

if (require("MASS")){
    .W <- Womenlf
    .W$partic <- factor(.W$partic, levels=c("not.work", "parttime", "fulltime"))
    poTest(polr(partic ~ hincome + children + region, data=.W))
}