pcX {eba}R Documentation

Paired-Comparison Design Matrix

Description

Computes a paired-comparison design matrix.

Usage

pcX(nstimuli)

Arguments

nstimuli number of stimuli in the paired-comparison design

Details

The design matrix can be used when fitting a Bradley-Terry-Luce (BTL) model by means of glm.

Value

A matrix having (nstimuli-1)*nstimuli/2 rows and nstimuli columns.

See Also

OptiPt, glm.

Examples

data(celebrities)  # absolute choice frequencies
btl <- OptiPt(celebrities)
summary(btl)

btl.glm <- glm(cbind(btl$y1, btl$y0) ~ pcX(9)[,-1] - 1, binomial)
summary(btl.glm)  # BTL model does not fit these data!

[Package eba version 1.4-0 Index]