Potty Parity

The authors drew inspiration from the following two sources. First, the textbook of Operations Management, 2nd ed., McGraw-Hill Higher Education by Gerard Cachon and Christian Terwiesch (2019) contains a mini-case of potty parity, which is used to illustrate queueing concepts. Second, the authors’ dear colleague, Joe Milner, gave the following exam question for the MBA OM core course at Rotman in 2020, which ignited the idea of writing this paper: Which of the following best reflects the pooling capacity to reduce restroom queue lengths? (a) Add more toilets to increase capacity. (b) Install a flexible partition that can alter the size of the women’s and the men’s restrooms. (c) Convert the separate men’s and women’s rooms into a single unisex restroom (that both men and women can use). (d) Remove mirrors in the restroom to decrease the time users spend in the restroom. (e) Add automatic flush capability to each toilet to decrease processing times. The answer of this stimulating question is- (c). In addition, the authors thank Omid Mousavi for guidance on architecture illustrations. The authors also thank the department editor, associate editor, and three anonymous reviewers for valuable comments and suggestions on the manuscript throughout the whole review process. Finally, a companion case, published in INFORMS Transactions on Education in September 2025, was awarded the first place in the 2024 INFORMS Case Competition.