We propose a semiparametric first-difference estimator for panel censored-selection models where the selection equation is of tobit type. The estimator allows the unit-specific term to be arbitrarily related to regressors. The estimator minimizes a convex function and does not require any smoothing. A simulation study is provided comparing our proposal with the estimators of Wooldridge (Journal...

In this paper, a class of quintic systems is investigated. The first 13 focal values are computed with the aid MATHEMATICA. Then necessary conditions integrability and linearizability obtained sufficiency every condition proved. Meanwhile, bifurcation limit cycles discussed, can be bifurcated from origin. As far as number enclosing an isolated singular point concerned, so best result for elemen...