Does L.A. count its homeless, or make its best guess? A little of both, it turns out

Gospel musician Clemmie Williams was living homeless in North Hollywood Park in January, when a count of homeless people is overseen by the Los Angeles Homeless Services Authority. Although the change does not affect the countywide totals reported to the U.S. Department of Housing and Urban Development, it highlights an uncomfortable truth about LAHSA’s annual reports: The much-discussed “counts” of homeless people, which are expressed with absolute precision, aren’t truly counts, but estimates, subject to statistical error. “I thought we really should be recording this error,” said Patricia St. Clair, statistical analysis director for the USC Homeless Count team. Because those numbers are based on a sample — even though an unusually large one — they are subject to statistical error, a fact that LAHSA has never acknowledged in its annual presentations, which report an exact number of how many people were “counted.” Behind the scenes, USC’s Data Core, which won the homeless contract in 2017, has worked diligently to refine and improve an endeavor that, by its nature, cannot achieve perfect accuracy. As St. Clair and team leader Benjamin Henwood acknowledge, the statistical modeling is only one part, and possibly the smallest part, of the error in the annual “count.” There’s no way of accounting for the mistakes that come from the annual outpouring of civic engagement that generates the raw numbers for USC’s analysis.