mbt: Mallows-Bradley-Terry Model

In eba: Elimination-by-Aspects Models

Description

Fits a Mallows-Bradley-Terry (MBT) model by maximum likelihood.

Usage

mbt(data, bootstrap = FALSE, nsim = 1000, ...)

Arguments

data	a data frame, the first t columns containing the ranks, the (t + 1)th column containing the frequencies
bootstrap	logical. Return a parametric bootstrap p-value?
nsim	number of bootstrap replicates
...	further aguments passed to simulate

Details

mbt provides a front end for glm. See Critchlow and Fligner (1991) and Mallows (1957) for details.

Value

coefficients	a vector of parameter estimates (scale values) constrained to sum to unity
goodness.of.fit	the goodness of fit statistic including the likelihood ratio fitted vs. saturated model (-2logL), the degrees of freedom, the p-value of the corresponding chi-square distribution, and if bootstrap is TRUE the bootstrap p-value
perm.idx	the names of the non-zero frequency ranks
y	the vector of rank frequencies including zeros
mbt.glm	the output from a call to glm

Author(s)

Florian Wickelmaier

References

Critchlow, D.E., & Fligner, M.A. (1991). Paired comparison, triple comparison, and ranking experiments as generalized linear models, and their implementation in GLIM. Psychometrika, 56, 517–533. doi: 10.1007/bf02294488

Mallows, C.L. (1957). Non-null ranking models. I. Biometrika, 44, 114–130. doi: 10.1093/biomet/44.1-2.114

See Also

tartness, glm.

Examples

data(tartness)        # tartness rankings of salad dressings (Vargo, 1989)
mbt(tartness, bootstrap=TRUE, nsim=500)  # fit Mallows-Bradley-Terry model

Example output

Mallows-Bradely-Terry (MBT) models

Parameter estimates:
     a       b       c       d  
0.0912  0.5182  0.2317  0.1588  

Goodness of fit (-2 log likelihood ratio):
	G2(20) = 22.25, p = 0.3272, bootstrap p = 0.098

eba documentation built on Jan. 13, 2021, 10:12 a.m.