TY - JOUR A1 - Engelman, M. A1 - Caswell, H. A1 - Agree, E.M. T1 - Why do lifespan variability trends for the young and old diverge? A perturbation analysis Y1 - 2014 DO - 10.4054/DemRes.2014.30.48 JF - Demographic Research VL - 30 IS - 48 ER -