poTest: Test for Proportional Odds in the Proportional-Odds...

Description Usage Arguments Value Author(s) References Examples

View source: R/poTest.R

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

1
2
3
4
5
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 jfox@mcmaster.ca

References

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

Examples

1
2
3
4
5
if (require("MASS")){
    .W <- Womenlf
    .W$partic <- factor(.W$partic, levels=c("not.work", "parttime", "fulltime"))
    poTest(polr(partic ~ hincome + children + region, data=.W))
}

Example output

Loading required package: carData
Loading required package: MASS

Tests for Proportional Odds
polr(formula = partic ~ hincome + children + region, data = .W)

                b[polr] b[>not.work] b[>parttime] Chisquare df Pr(>Chisq)    
Overall                                               26.47  6    0.00018 ***
hincome         -0.0569      -0.0453      -0.1011      5.73  1    0.01666 *  
childrenpresent -2.0099      -1.6043      -2.7266     17.90  1    2.3e-05 ***
regionBC         0.1530       0.3420      -0.7228      2.69  1    0.10114    
regionOntario    0.2687       0.1878       0.0620      0.07  1    0.78563    
regionPrairie    0.4797       0.4719       0.3501      0.05  1    0.82760    
regionQuebec    -0.0711      -0.1731      -0.2974      0.07  1    0.79252    
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

car documentation built on June 27, 2021, 5:07 p.m.