logsum | R Documentation |
The 'logsum' function computes the inclusive value, or inclusive utility, which is used to compute the surplus and to estimate the two steps nested logit model.
logsum(
coef,
X = NULL,
formula = NULL,
data = NULL,
type = NULL,
output = c("chid", "obs")
)
coef |
a numerical vector or a 'mlogit' object, from which the 'coef' vector is extracted, |
X |
a matrix or a 'mlogit' object from which the 'model.matrix' is extracted, |
formula |
a formula or a 'mlogit' object from which the 'formula' is extracted, |
data |
a 'data.frame' or a 'mlogit' object from which the 'model.frame' is extracted, |
type |
either '"group"' or '"global"' : if a 'group' argument has been provided in the 'mlogit.data', the inclusive values are by default computed for every group, otherwise, a unique global inclusive value is computed for each choice situation, |
output |
the shape of the results: if '"chid"', the results is a vector (if 'type = "global"') or a matrix (if 'type = "region"') with row number equal to the number of choice situation, if '"obs"' a vector of length equal to the number of lines of the data in long format is returned. |
The inclusive value, or inclusive utility, or log-sum is the log of the denominator of the probabilities of the multinomial logit model. If a '"group"' variable is provided in the '"mlogit.data"' function, the denominator can either be the one of the multinomial model or those of the lower model of the nested logit model.
If only one argument ('coef') is provided, it should a 'mlogit' object and in this case, the 'coefficients' and the 'model.matrix' are extracted from this model.
In order to provide a different 'model.matrix', further arguments could be used. 'X' is a 'matrix' or a 'mlogit' from which the 'model.matrix' is extracted. The 'formula'-'data' interface can also be used to construct the relevant 'model.matrix'.
either a vector or a matrix.
Yves Croissant
[mlogit()] for the estimation of a multinomial logit model.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.