  In this paper it is shown that under certain conditions there is a
relationship between the parameter estimation of the Fellegi--Sunter
probabilistic linkage model and dual system estimation. This relationship can
be used as the basis of an approach to population size estimation. In this case
it is sufficient to estimate the parameters of the linkage model in order to
obtain the population size estimate. Neither classification of the record pairs
into links and non-links, nor forcing the records into a series of 1-1 matches,
nor clerical review of the potential links is required. The accuracy of the
proposed estimator appears to be bounded by the accuracy of the dual system
estimator with perfect linkage and it diminishes as the discriminatory power of
the linkage variables decreases.
