CaseDeletion            Case deletion analysis for Heckman selection
                        model
HeckmanEM               Fit the Normal, Student-t or Contaminated
                        normal Heckman Selection model
HeckmanEM.criteria      Model selection criteria for the Heckman
                        Selection model
HeckmanEM.envelope      Envelope for the Heckman Selection model
HeckmanEM.infomat       Standard error estimation for the Heckman
                        Selection model by the Information Matrix
Influence               Influence Analysis for the Heckman Selection
                        model
rHeckman                Data generation from the Heckman Selection
                        model (Normal, Student-t or CN)
