IMR {ssmodels} | R Documentation |
Inverse Mills Ratio (IMR) Calculation
Description
Computes the column vector of the Inverse Mills Ratio (IMR) from a Probit selection equation.
Usage
IMR(selection, data = sys.frame(sys.parent()))
Arguments
selection |
A formula specifying the selection equation. |
data |
A data frame containing the variables in the model. |
Details
This function fits a Probit model to the provided selection equation and returns the Inverse Mills Ratio (IMR) for each observation. The IMR is useful for correcting sample selection bias in regression models, following the classical Heckman approach.
Value
A numeric matrix with one column containing the IMR values for each observation.
Examples
data(MEPS2001)
attach(MEPS2001)
selectEq <- dambexp ~ age + female + educ + blhisp + totchr + ins + income
IMR(selectEq, data = MEPS2001)
[Package ssmodels version 2.0.1 Index]