The data for this question consists of a sample of 50 persons from the 1967-1980 Evans County Study. There are two basic independent variables of interest: AGE and chronic disease status (CHR), where CHR is coded as 0=none, l=chronic disease. A product term of the form AGE*CHR is also considered. The dependent variable is time until death, and the event is death. The primary question of interest concerns whether CHR, considered as the exposure variable, is related to survival time, controlling for AGE. The output of computer results for this question is given as follows: