twostep {ssmodels}

Heckman's two-step method

Description

Estimate model parameters via two-step method

Usage

twostep(selection, outcome, data = sys.frame(sys.parent()))

Arguments

selection

Selection equation.

outcome

Primary Regression Equation.

data

Database.

Value

Returns a numerical vector with the parameter estimates of the Classical Heckman model via a two-step method. For more information see Heckman (1979)

References

James J Heckman (1979). “Sample selection bias as a specification error.” Econometrica: Journal of the econometric society, 153–161.

Examples

data(MEPS2001)
attach(MEPS2001)
selectEq <- dambexp ~ age + female + educ + blhisp + totchr + ins + income
outcomeEq <- lnambx ~ age + female + educ + blhisp + totchr + ins
twostep(selectEq, outcomeEq)