QUALITATIVE CHANGES IN COHORT HETEROGENEI TY - IMPACT ON THE MEASUREMENT AND PROJECTION OF THE DEMAND FOR HEALTH-CARE

This paper examines the effect of cohort heterogeneity upon the potent ial needs for assistance in ADL and IADL of an aging population. Varia bles that are important predictors of the differentiating pattern of p erceived needs in the older population are subject to on-going changes as a result of cohort differentiation and cohort succession in the ol der ages. For those reasons, a forecasting methodology involving three phases has been developed: an identification phase of the key explana tory variables, a demographic-projection phase of socio-demographic va riables identified as key variables and a phase in which risk-factor p robabilities are applied to the demographic-projection output to deter mine the overall impact of the population change. The use of logistic regression is shown as the best strategy to determine risk-factor prob abilities. This method is applied to measure the assistance needed in ADL and IADL by disabled elderly persons in Quebec. The results point to the need to consider changes in intra-cohort heterogeneity between new cohorts entering the older population and old ones leaving it.