model.matrix.selection {sampleSelection} | R Documentation |
Design Matrix of Selection Models
Description
Create design matrix of sample selection models
Usage
## S3 method for class 'selection'
model.matrix(object, part = "outcome", ... )
Arguments
object |
object of class |
part |
character string indication which design matrix/matrices to extract: "outcome" for the design matrix/matrices of the outcome equation(s) or "selection" for the design matrix of the selection equation. |
... |
further arguments passed to other methods
(e.g. |
Value
If argument part
is "selection"
,
the design matrix of the selection equation is returned.
If argument part
is "outcome"
,
the design matrix of the outcome equation (tobit-2 or treatment
model)
or a list of two outcome matrices (tobit-5 model) is returned.
All unobserved outcomes, including the corresponding explanatory
variables
are set to NA
, even in case where
valid values were supplied
for estimation.
Author(s)
Arne Henningsen
See Also
model.matrix
, selection
,
model.frame.selection
, and selection-methods
.