effects.mlogit | R Documentation |
The 'effects' method for 'mlogit' objects computes the marginal effects of the selected covariate on the probabilities of choosing the alternatives
## S3 method for class 'mlogit'
effects(
object,
covariate = NULL,
type = c("aa", "ar", "rr", "ra"),
data = NULL,
...
)
object |
a 'mlogit' object, |
covariate |
the name of the covariate for which the effect should be computed, |
type |
the effect is a ratio of two marginal variations of the probability and of the covariate ; these variations can be absolute '"a"' or relative '"r"'. This argument is a string that contains two letters, the first refers to the probability, the second to the covariate, |
data |
a data.frame containing the values for which the effects should be calculated. The number of lines of this data.frame should be equal to the number of alternatives, |
... |
further arguments. |
If the covariate is alternative specific, a J \times J
matrix is
returned, J
being the number of alternatives. Each line contains the
marginal effects of the covariate of one alternative on the probability to
choose any alternative. If the covariate is individual specific, a vector of
length J
is returned.
Yves Croissant
[mlogit()] for the estimation of multinomial logit models.
data("Fishing", package = "mlogit")
library("zoo")
Fish <- mlogit.data(Fishing, varying = c(2:9), shape = "wide", choice = "mode")
m <- mlogit(mode ~ price | income | catch, data = Fish)
# compute a data.frame containing the mean value of the covariates in
# the sample
z <- with(Fish, data.frame(price = tapply(price, idx(m, 2), mean),
catch = tapply(catch, idx(m, 2), mean),
income = mean(income)))
# compute the marginal effects (the second one is an elasticity
## IGNORE_RDIFF_BEGIN
effects(m, covariate = "income", data = z)
## IGNORE_RDIFF_END
effects(m, covariate = "price", type = "rr", data = z)
effects(m, covariate = "catch", type = "ar", data = z)
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