RprobitB_normalization {RprobitB} | R Documentation |
Create object of class RprobitB_normalization
Description
This function creates an object of class RprobitB_normalization
,
which determines the utility scale and level.
Usage
RprobitB_normalization(
level,
scale = "Sigma_1,1 := 1",
form,
re = NULL,
alternatives,
base,
ordered = FALSE
)
## S3 method for class 'RprobitB_normalization'
print(x, ...)
Arguments
level |
The alternative name with respect to which utility differences are computed. Currently, only differences with respect to the last alternative can be computed. |
scale |
A character which determines the utility scale. It is of the form
|
form |
A
Multiple covariates (of one type) are separated by a In the ordered probit model ( |
re |
A character (vector) of covariates of |
alternatives |
A character vector with the names of the choice alternatives.
If not specified, the choice set is defined by the observed choices.
If |
base |
A character, the name of the base alternative for covariates that are not
alternative specific (i.e. type 2 covariates and ASCs). Ignored and set to
|
ordered |
A boolean, |
x |
An object of class |
... |
Currently not used. |
Details
Any choice model has to be normalized with respect to the utility level and scale.
For level normalization,
{RprobitB}
takes utility differences with respect to one alternative. For the ordered model where only one utility is modeled,{RprobitB}
fixes the first utility threshold to 0.For scale normalization,
{RprobitB}
fixes one model parameter. Per default, the first error-term variance is fixed to1
. This is specified viascale = "Sigma_1,1 := 1"
. Alternatively, any error-term variance or any non-random coefficient can be fixed.
Value
An object of class RprobitB_normalization
, which is a list of
-
level
, a list with the elementslevel
(the number of the alternative specified by the inputlevel
) andname
(the name of the alternative, i.e. the inputlevel
), or alternativelyNA
in the ordered probit case, and
scale
, a list with the elementsparameter
(either"s"
for an element ofSigma
or"a"
for an element ofalpha
), the parameterindex
, and the fixedvalue
. Ifparameter = "a"
, also thename
of the fixed effect.
Examples
RprobitB:::RprobitB_normalization(
level = "B",
scale = "price := -1",
form = choice ~ price + time + comfort + change | 1,
re = "time",
alternatives = c("A", "B"),
base = "A"
)