Estimation of the Parameters in the Lognormal Distribution with Grouped and Right-Censored Data

In this paper we consider the estimation problem in the situation where the life of some products follows a lognormal distribution, and the observed data are grouped and right-censored. A necessary and sufficient condition for the existence and uniqueness of the Maximum Likelihood Estimate (MLE) of unknown parameters is given. Furthermore, we have estimated the unknown parameters by EM algorithm.