Marketing Science

—“The Markov visitation” (It often seems as if the basic tool of operations research in marketing is the Markov chain. There are few O.R. people who have looked into marketing who haven't attempted to apply the tool.) Researchers have also invented a variety of ways to deal with variable purchase intervals, some as simple as using two chains which interweave. One assesses whether a purchase will be made in the next time interval and the second deals with the brand choice.

—The mailbag

 –“To the Editor” by R. A. Longman, Fullerton, California