A second simple example of economic thinking is Friedman's Law for Finding Men's Washrooms--"Men's rooms are adjacent, in one of the three dimensions, to ladies' rooms." One of the builder's objectives is to minimize construction costs; it costs more to build two small plumbing stacks (the set of pipes needed for a washroom) than one big one. So it is cheaper to put washrooms close to each other in order to get them on the same stack. That does not imply that two men's rooms on the same floor will be next to each other (although men's rooms on different floors are usually in the same position, making them adjacent vertically).Putting them next to each other reduces the cost, but separating them gets them close to more users. But there is no advantage to having men's and ladies' rooms far apart, since they are used by different people, so they are almost always put on the same stack. The law does not hold for buildings constructed on government contracts at cost plus 10 percent.
Ironically, another counterexample to this law occurs on the second floor of Rosenwald Hall at University of Chicago (home of the economics department). The women's bathroom is across from the stairwell, while the men's bathroom is down the hall (on the other side of the hallway).