gFormula function

Model Formula for Multinomial Logit Models

Four kind of variables are used in multinomial choice models with individual heterogeneity: alternative specific and individual specific variables; variables for the mean of the random parameters (deterministic taste variations), and variables for the scale function. gFormula deals with this type of models using suitable methods to extract the elements of the model.

gFormula(object)

is.gFormula(object)

## S3 method for class 'gFormula'
model.frame(formula, data, ..., lhs = NULL, rhs = NULL)

## S3 method for class 'gFormula'
model.matrix(object, data, rhs = NULL, Q = NULL, ...)

Arguments

• object: a formula for the gFormula function, for the model.matrix method, a gFormula object,
• formula: a gFormula object,
• data: a data.frame,
• ...: further arguments.
• lhs: see Formula,
• rhs: see Formula,
• Q: number of classes for the latent class model,