Record linkage, sometimes referred to as information retrieval (frakes and baeza-yates 1992), is needed for the creation, unduplication, and maintenance of name and address lists. this paper describes string comparators and their effect in a production matching system. because many lists have typographical errors in more than 20% of first names and also in last names, effective methods for dealing with typographical error can greatly improve matching efficacy. the enhanced methods of approximate string comparison deals with typographical variations and scanning errors. the values returned by the string comparator are used in a statistical model for adjusting parameters that are automatically estimated by an expectation-maximization algorithm for latent class, log linear models of the type arising in the fellegi-sunter model of record linkage (1969). overall matching efficacy is further improved by linear assignment algorithm that forces 1-1 matching. modern record linkage represents a collection of methods from three different disciplines: computer science, statistics, and operations research. while the foundations are from statistics, beginning with the seminal work of newcombe (newcombe et al. 1959, also newcombe 1988) and fellegi and sunter (1969), the means of implementing the methods have primarily involved computer science.