Data reflecting: (a) physiologic test results; (b) age, sex, and physique; (c) clinical findings; and (d) exposures to cigarette smoking were collected on a subset of the population sample being studied. The data were subjected to component analysis, a method by which an attempt is made to transform a large number of interrelated variables into a smaller number of uncorrelated variables. A large electronic computer was used. Analyses were run on several subsets of variables and for several samples. In practically all cases the first three components were associated with two aspects of pulmonary function and with body weight and accounted for approximately three-fourths of the total variance.