Abstract
The EM algorithm described by Dempster, Laird and Rubin (1977) is reviewed with the purpose of clarifying several misconceptions in the statistical and econometric literature. The clarification lead to several applications of the algorithm to models that have appeared to be less tractable. The relationship between the EM algorithm and the method of scoring is also explained, providing estimators of the score and the information from the EM algorithm. The EM algorithm is extended to missing-data problems and an estimation method based on simulations.