View source: R/model_fitting.R
RprobitB_normalization | R Documentation |
RprobitB_normalization
This function creates an object of class RprobitB_normalization
,
which determines the utility scale and level.
RprobitB_normalization( level, scale = "Sigma_1,1 := 1", form, re = NULL, alternatives, base, ordered = FALSE )
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, |
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 to 1
.
This is specified via scale = "Sigma_1,1 := 1"
.
Alternatively, any error-term variance or any non-random coefficient
can be fixed.
An object of class RprobitB_normalization
, which is a list of
level
, a list with the elements level
(the number of the
alternative specified by the input level
) and name
(the name of
the alternative, i.e. the input level
), or alternatively
NA
in the ordered probit case,
and scale
, a list with the elements parameter
(either "s"
for
an element of Sigma
or "a"
for an element of alpha
), the
parameter index
, and the fixed value
. If parameter = "a"
, also
the name
of the fixed effect.
RprobitB:::RprobitB_normalization( level = "B", scale = "price := -1", form = choice ~ price + time + comfort + change | 1, re = "time", alternatives = c("A", "B"), base = "A" )
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