“…For instance, one of the determinants commonly taken into account in demand-based studies is income. However, estimates of the income elasticity of health care demand in microeconomic studies (which are often used for demand-based forecasting (Hall & Mejia, 1978;Klarman, 1969Klarman, , 1973) vary widely, even if they cover similar geographic areas and time periods, suggesting that these estimates are quite uncertain (see, for instance, (R. Anderson & Benham, 1970;Fein, 1967;P. J. Feldstein, 1964;Gorham, 1967;Newhouse & Phelps, 1976;Rosett & Huang, 1973;Silver, 1970;Stigler, 1956)).…”