@article{KWW2006b,
    TITLE = {Relationships between Period and Cohort Life Expectancy: Gaps and
             Lags},
   AUTHOR = {Joshua R. Goldstein and Kenneth W. Wachter},
  JOURNAL = {Population Studies},
   VOLUME = {60},
   NUMBER = {3},
    PAGES = {257--269},
    MONTH = {November},
     YEAR = {2006},
       ID = {info:doi/10.1080/00324720600895876},
 ABSTRACT = {This paper offers an empirical and analytic foundation for
             regarding period life expectancy as a lagged indicator of the
             experience of real cohorts in populations experiencing steady
             improvement in mortality. We find that current period life
             expectancy in the industrialized world applies to cohorts born some
             40-50 years ago. Lags track an average age at which future years of
             life are being gained, in a sense that we make precise. Our
             findings augment Ryder's classic results on period-cohort
             translation.},
   }