title: A reducible four-parameter system of model life tables.
abstract: Abstract   In this paper a four-parameter extension of Brass's relational system of model life tables is suggested that (1) matches a wide range of empirical age patterns of mortality, (2) is easy to apply, especially to partial life tables, and (3) contains demographically meaningful parameters. A test of the model on a set of 62 empirical life tables indicates that four parameters are necessary and sufficient for fitting a wide range of mortality patterns. A further test on an historical series of Swedish life tables reveals a consistent pattern of mortality change. Examination of the parameters for a set of geographicallyrelated life tables suggests a way to define families of life tables. Identification of such temporal and spatial relationships allows the model to be reduced to a form with twoor three-parameters for application to incomplete or inaccurate data.
authors.affiliation: a      Population Studies Center   ,  University of Pennsylvania   ,  Pennsylvania.
authors.forename: D C
authors.initials: DC
authors.lastname: Ewbank
authors.forename: J C
authors.initials: JC
authors.lastname: Gomez De Leon
authors.forename: M A
authors.initials: MA
authors.lastname: Stoto