Estimating the Expectation of Life at Old Ages: Comments on the Article by Mitra

Family reconstitution studies assess demographic behaviour for that section of the population that remains in the parish of their birth. Although there has been considerable discussion of whether or not these non-migrants are representative of the population as a whole, the distorting effects of migration censoring have not been adequately considered. This paper shows that even when the demographic behaviour of non-migrants is identical to that of the general population, migration-censoring will significantly bias family reconstitution results. In particular, existing family reconstitution studies underestimate both age at marriage and life expectancy. The paper assesses the potential magnitude of bias introduced by migration, and suggests several new techniques for correcting the errors.