HCinitial               Two-Step Method for Parameter Estimation of the
                        Classical Heckman Model
HeckmanBS               Heckman-BS Model Fit Function
HeckmanCL               Classic Heckman Model Fit Function
HeckmanGe               Generalized Heckman Model Estimation
HeckmanSK               Skew-Normal Sample Selection Model Fit Function
HeckmantS               Heckman-t Model Fit Function
IMR                     Inverse Mills Ratio (IMR) Calculation
MEPS2001                Medical Expenditure Panel Survey
Mroz87                  U.S. Women's Labor Force Participation
PSID2                   Panel Study of Income Dynamics
RandHIE                 RAND Health Insurance Experiment
nhanes                  US National Health and Nutrition Examination
                        Study
ssmodels                ssmodels: Sample Selection Models in R
step2                   Heckman's Two-Step Method
summary.HeckmanBS       Summary of Birnbaum-Saunders Heckman Model
summary.HeckmanCL       Summary of Classic Heckman Model
summary.HeckmanGe       Summary of Generalized Heckman Model
summary.HeckmanSK       Summary of Skew-Normal Heckman Model
summary.HeckmantS       Summary of Heckman-t Model
twostep                 Two-Step Estimation of the Classic Heckman
                        Model
