multgee (version 1.0)

intrinsic.pars: Intrinsic Parameters Estimation

Description

Utility function to assess the underlying association pattern.

Usage

intrinsic.pars(response, id, repeated, ncategories, rscale = "ordinal")

Arguments

response

a vector that indicates the response variables.

id

a vector that identifies the subjects.

repeated

a vector that identifies the order of the observations within each subject.

ncategories

a positive constant that indicates the maximum number of the observed response categories.

rscale

a character string that indicates the nature of the response scale. Options include "ordinal" or "nominal".

Value

• Returns a vector with the estimated intrinsic parameters.

Details

Simulation studies in Touloumis, Agresti and Kateri (2012) suggested that if the range of the intrinsic parameter estimates is small then simple local odds ratios structures should adequately approximate the association pattern. The intrinsic parameters are estimated under the heterogeneous uniform association model for ordinal response categories and under the RC-G model with homogeneous score parameters for nominal response categories.

References

Touloumis, A., Agresti, A. and Kateri, M. (2012). GEE for multinomial responses using a local odds ratios parameterization. Submitted.

See Also

nomLORgee and ordLORgee

Examples

data(arthritis)
intrinsic.pars(arthritis$y,arthritis$id,arthritis$time,5)
The intrinsic parameters do not differ much. The 'uniform' local odds ratios
structure might be a good approximation for the association pattern.
set.seed(1)
data(housing)
intrinsic.pars(housing$y,housing$id,housing$time,3,rscale="nominal")
The intrinsic parameters seem to vary. The 'RC' local odds ratios structure
might be a good approximation for the association pattern.