APPLICATIONS OF THE EM ALGORITHM TO THE ANALYSIS OF LIFE LENGTH DATA

The parameters of the life length distribution of a given component ar e to be estimated. The observations on which inference is to be based are field data which are incomplete in some fashion. Thus, for example , the reported life length may include a period of unknown duration du ring which the component is not in use, the life length distribution m ay be affected by an unobserved environmental factor or the component may be part of a larger system, and failure mode analysis reveals only the module containing the failed component, not its identity. It is s hown how the EM algorithm can be used to calculate the maximum likelih ood estimates of the parameters of interest in these instances. The me thodology is applied to some data on the life lengths of electronic co mponents used in the telecommunications industry, yielding values that are similar to those obtained from complete observations on comparabl e components.