The basic statistical approach involved the specification of longitudinal logistic regression models wherein the principal's drinking status at time t+1 is a function of various attributes of principals such as age, gender, and education, their drinking status at time t, and the drinking status of their contacts at times t and t+1.(25) Generalized estimating equation procedures were used to account for multiple observations of the same principal across waves and across principal-contact pairings.(26) An independent working correlation structure for the clusters was assumed.(27)
