QUANTIFYING SYNCHRONY AMONG REPRODUCTIVE OR OTHER STATES

Synchrony among reproductive or other states is a widespread phenomeno n of significance in evolutionary theory. A model is presented for use in the measurement of the degree of synchrony in any set of behaviora l or biological states, such as menstrual cycling, pregnancy, or lacta tion. At a given time, maximum group synchrony occurs when all members of a group are in a single state, minimum synchrony occurs when equal numbers are in all states, and intermediate values of synchrony occur for other proportional representations of the states. The model yield s group synchrony scores ranging from 0 to 100 by standardizing the av erage of the absolute deviations among frequencies of occurrence in pa irs of states. In addition, individual synchrony is characterized by t he proportion of others who share an individual's state at a specified set of times. Properties of the model are discussed, simplified calcu lation procedures are presented, and the method's usefulness for compa rative purposes is illustrated. (C) 1995 Wiley-Liss, Inc.