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The reciprocation of friendship choices as revealed in a sociogram may be used to describe the social distance between persons in a large group. The probability of reciprocation is shown to be the result of a sequential choice process in which the best friend is chosen first, then second best, and so on, with the probability decreasing linearly with decreasing rank. The model derived from this process completely specifies the entire 8 by 8 matrix of reciprocations to the eighth friend level.
Foster et al. (Wed,) studied this question.