Key points are not available for this paper at this time.
This research was funded, in part, by National Institutes of Health grant No. 5-TO1-GM-01526. An earlier version of this paper was presented to a symposium, Methodology in Sociology, jointly sponsored by the Methodology Section of the American Sociological Association and Loyola University, Chicago, Illinois, June 1011, 1970. The authors are especially grateful to G. William Walster for his helpful comments on the earlier version of the paper.
Bohrnstedt et al. (Fri,) studied this question.