This function checks the input form
.
Arguments
- form
[
formula
]
A model description with the structurechoice ~ A | B | C
, wherechoice
is the name of the dependent variable (the choices),A
are names of alternative and choice situation specific covariates with a coefficient that is constant across alternatives,B
are names of choice situation specific covariates with alternative specific coefficients,and
C
are names of alternative and choice situation specific covariates with alternative specific coefficients.
Multiple covariates (of one type) are separated by a
+
sign. By default, alternative specific constants (ASCs) are added to the model. They can be removed by adding+0
in the second spot.In the ordered probit model (
ordered = TRUE
), theformula
object has the simple structurechoice ~ A
. ASCs are not estimated.- re
[
character()
|NULL
]
Names of covariates with random effects. Ifre = NULL
(the default), there are no random effects. To have random effects for the ASCs, include"ASC"
inre
.- ordered
[
logical(1)
]
IfTRUE
, the choice setalternatives
is assumed to be ordered from worst to best.
Value
A list that contains the following elements:
The input
form
.The name
choice
of the dependent variable inform
.The input
re
.A list
vars
of three character vectors of covariate names of the three covariate types.A boolean
ASC
, determining whether the model has ASCs.
See also
overview_effects()
for an overview of the model effects