extract3logit: Extract information from fitted models

In plot3logit: Ternary Plots for Trinomial Regression Models

Extract information from fitted models

Description

extract3logit() extracts all information which is relevant for computing the vector field(s) from the object passed to argument x. See Details for information on how new S3 methods of generic extract3logit() should be implemented.

Usage

extract3logit(x, ...)

## Default S3 method:
extract3logit(x, ...)

## S3 method for class 'clm'
extract3logit(x, ...)

## S3 method for class 'clm2'
extract3logit(x, ...)

## S3 method for class 'mlogit'
extract3logit(x, ...)

## S3 method for class 'model3logit'
extract3logit(x, ...)

## S3 method for class 'multinom'
extract3logit(x, ...)

## S3 method for class 'polr'
extract3logit(x, ...)

## S3 method for class 'vgam'
extract3logit(x, ...)

## S3 method for class 'vglm'
extract3logit(x, ...)

Arguments

x	an object of any of the classes listed above. If instead, a list is passed, it should be structured as described in section Details.
...	other arguments passed to other methods.

Details

When a specific method is not available for a fitted model, it is possible to pass a list to argument x. In that case, the list should consists of the following components (the order is irrelevant):

• levels: vector of possible values of the dependent variable. It should be a character vector of lenght three, whose first element is interpreted as the reference level, whereas the second and the third elements are associated to the first and second columns of matrix B respectively.

• B: matrix of regression coefficients. It should be a numeric matrix (or any coercible object) with two columns if the model is cardinal, with only one column if the model is ordinal. The number of rows should be equal to the number of covariates and the names of covariates should be added as row names. The intercepts should be included only in case of categorical models, whereas column names, if provided, are ignored.

• alpha: intercepts of ordinal models. It should be a numerical vector of length two if the model is ordinal, otherwise this component should be either set to NULL or missing.

• vcovB: covariance matrix of regression coefficients. It should be a numeric matrix (or any coercible object) where the number of rows and columns equals the number of elements of B. Rows and columns should be ordered according to the labels of the dependent variable (slower index), and then to the covariates (faster index).

If a new S3 method for generic extract3logit() has to be implemented, the following components may be set:

• readfrom: character with information about the function that returned the estimates in the form package::function (for example nnet::multinom, MASS::polr, ...)

In any case, once the list has been created, the new method should invoke the default method extract3logit.default() and return its ouput. By so doing, automatic checks and initialisations are run before the model3logit object is returned.

Value

An object of class model3logit.

See Also

plot3logit-package, field3logit().

plot3logit documentation built on July 19, 2022, 9:07 a.m.