The nine datasets used included: for pulmonary data, the Childhood Respiratory Disease Study, the Netherlands data from Vlagtwedde and Vlaardingen, the Boston Police Study, the Fletcher Study data from England; for cardiopulmonary data, the Veterans Administration Normative Aging Study; for blood pressure data, the Wales Study, the Zinner/Kass Study, the Lee/Zinner Study, and the East Boston Childhood Blood Pressure Study. For each of the nine datasets the following models were fitted and compared for adults, children, and for adults and children combined: autoregressive models both serial-correlation and state-dependence; random-effects models; regression models with intraclass correlation structure; general linear models; models based on fitting slopes to individual persons. New methods for analyzing longitudinal data were developed and included fitting of higher-order autoregressive models with unequally spaced data, nonparametric methods, familial and other clustering effects in the analysis of longitudinal pulmonary function data, robust methods, empirical Bayes methods for estimation of slopes, and hierarchial models based on old and new methods.