HMSkew-nonlin: Specify a Skew-Symmetric Association in a gnm Model Formula
In logmult: Log-Multiplicative Models, Including Association Models

HMSkew

R Documentation

Specify a Skew-Symmetric Association in a gnm Model Formula

Description

A function of class "nonlin" to specify a van der Heijden & Mooijaart (1995) skew-symmetric association in the formula argument to gnm.

Usage

HMSkew(row, col, inst = NULL)

Arguments

`row`	the levels of the row variable
`col`	the levels of the column variable
`inst`	a positive integer specifying the instance number of the term

Details

This function is used by hmskew to fit skew-symmetric models proposed by van der Heijden & Mooijaart (1995) and their variants. It can be used directly to fit custom variants of the model not supported by hmskew.

This function combines its arguments in the following way:

HMSkew(i, j) = ν_i μ_j - μ_i ν_j

where HMSkew(i, j) is the skew association for the cell at the intersection of row i and column j of the table. See reference for mathematical details.

Value

A list with the required components of a "nonlin" function:

`predictors`	the expressions passed to `Mult`
`term`	a function to create a deparsed mathematical expression of the term, given labels for the predictors.
`call`	the call to use as a prefix for parameter labels.

Author(s)

Milan Bouchet-Valat

References

van der Heijden, P.G.M., and Mooijaart, A. (1995). Some new log bilinear models for the analysis of asymmetry in a square contingency table. Sociol. Methods and Research 24, 7-29.