This function gives an overview of the effect names, whether the covariate is alternative-specific, whether the coefficient is alternative-specific, and whether it is a random effect.
Usage
overview_effects(
form,
re = NULL,
alternatives,
base = tail(alternatives, 1),
ordered = FALSE
)
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
.- alternatives
[
character()
]
The names of the choice alternatives. If not specified, the choice set is defined by the observed choices.If
ordered = TRUE
,alternatives
is assumed to be specified with the alternatives ordered from worst to best.- base
[
character(1)
]
The name of the base alternative for covariates that are not alternative specific (i.e. type 2 covariates and ASCs).Ignored and set to
NULL
if the model has no alternative specific covariates (e.g. in the ordered probit model).By default,
base
is the last element ofalternatives
.- ordered
[
logical(1)
]
IfTRUE
, the choice setalternatives
is assumed to be ordered from worst to best.
Value
A data.frame
, each row is a effect, columns are the effect name
"effect"
, and booleans whether the covariate is alternative-specific
"as_value"
, whether the coefficient is alternative-specific
"as_coef"
, and whether it is a random effect "random"
.
See also
check_form()
for checking the model formula specification.
Examples
overview_effects(
form = choice ~ price + time + comfort + change | 1,
re = c("price", "time"),
alternatives = c("A", "B"),
base = "A"
)
#> effect as_value as_coef random
#> 1 comfort TRUE FALSE FALSE
#> 2 change TRUE FALSE FALSE
#> 3 ASC_B FALSE TRUE FALSE
#> 4 price TRUE FALSE TRUE
#> 5 time TRUE FALSE TRUE