John Dutton Conant Little (February 1, 1928 – September 27, 2024) was an American operations researcher and marketing scientist. He was an Institute Professor at the Massachusetts Institute of Technology and a longtime faculty member of the MIT Sloan School of Management. He is best known for Little's law, the queueing-theory relation <math>L=\lambda W</math>, which states that the long-run average number of items in a stable system equals the effective arrival rate multiplied by the average time an item spends in the system.
Little's work connected mathematical modeling, computation, and managerial practice. His research included queueing theory, traffic-signal control, optimization, advertising models, consumer-choice models, decision-support systems, and marketing automation. He was also a co-author of a 1963 paper on the travelling salesman problem that presented a branch-and-bound algorithm and helped establish the term in optimization.
At MIT Sloan, Little became one of the central figures in the development of marketing science. His 1970 article "Models and Managers: The Concept of a Decision Calculus" argued that management-science models should be understandable, controllable, robust, adaptive, complete, easy to communicate with, and useful to managers rather than merely mathematically elegant. Later commentators described this work as influential in shifting marketing science toward models that joined analytical rigor with managerial relevance.
Early life and education
Little was born in Boston on February 1, 1928, and grew up in Andover, Massachusetts. He attended Phillips Academy and entered MIT as an undergraduate in 1945.
At MIT, Little originally continued in physics, but under the influence of Philip M. Morse he moved into the emerging field of operations research. MIT and INFORMS sources describe the dissertation as the first PhD in operations research in the United States, or among the first work formally granted in that field.
The relationship had been used informally before Little's proof. Little later wrote that the formula seemed intuitively obvious but was difficult to establish in adequate generality.
Little's early operations-research work also included computerized methods for setting fixed-time traffic signals. At MIT, he worked on traffic-signal coordination and traffic-flow optimization, using computational approaches rather than the hand-drawn graphical methods common in earlier practice. The article is an early example of marketing models that adapt to observed data over time.
His 1970 article "Models and Managers: The Concept of a Decision Calculus" became one of his most influential works. With Peter Guadagni, he later developed a logit model of brand choice calibrated on scanner-panel data, a paper that became a classic in empirical marketing science.