model.matrix.selection {sampleSelection} | R Documentation |
Create design matrix of sample selection models
## S3 method for class 'selection' model.matrix(object, part = "outcome", ... )
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. |
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 of a tobit-2 model
or a list that contains the design matrices of the (two) outcome equations
of a tobit-5 model is returned.
All values of observations (rows of the design matrix)
that were not selected for estimating the corresponding outcome equation
are set to NA
.
Arne Henningsen
selection
,
model.matrix
, and model.matrix.binaryChoice