TY - JOUR A1 - Wooldridge, J.M. T1 - Simple solutions to the initial conditions problem in dynamic nonlinear panel data models with unobserved heterogeneity Y1 - 2005 DO - 10.1002/jae.770 JF - Journal of Applied Econometrics VL - 20 IS - 1 SP - 39 EP - -54 ER -