Heckman’s (1976, 1979) sample selection model has been employed in many studies of linear or nonlinear regression applications. It is well known that ignoring the sample selectivity problem may result in inconsistency of the estimator due to the correlation between the statistical errors in...

Heckman’s (Ann Econ Soc Meas 15:475–492, <CitationRef CitationID="CR5">1976</CitationRef>; Econometrica 47(1):153–161, <CitationRef CitationID="CR6">1979</CitationRef>) sample selection model has been employed in many applications of linear or nonlinear regression studies. It is well known that ignoring the sample selectivity may result in estimation bias of the estimator....</citationref></citationref>