Let's say there's an acre of land and the community is deciding which purposes it wants to zone that land for. Let's also say that you could reliably estimate the average number of people present on that acre for each of several development proposals. That Popular Land Use Metric (PLUM) wouldn't be the only metric we'd want to consider for zoning purposes, but it could well be the most important.
To arrive at the PLUM estimate, you'd have to generate a large sample size of random moments in time throughout the year and then estimate the number of people you'd expect to be present on that acre at each of those moments. Then average the estimates.
Obviously, some vital land uses would have low PLUMs. A water treatment plant might have only a handful of employees present but still be meeting the needs of a large population. But I'd guess that the higher the PLUM estimate for a land use, the more valuable that land use would generally be. After all, people have a great deal of choice concerning where they place themselves and so a simple count of people who've chosen a certain location to be present in tells us more a about the value people assign to a land use than perhaps even free market evaluations could determine.
PLUM answers the most important University of Chicago question: "How does it work in theory?"
It could be that someone else has come up with the PLUM idea before, but I've never run into it. Until I hear otherwise, I'm claiming it for my own.