Using the Capture–Recapture Technique to Supplement a Point-in-Time Count of Homeless Adults in Kittitas County, Washington.

This article focuses on comparing capture–recapture (CRC) methodology with the point-in-time (PIT) count for estimating homelessness in Kittitas County, Washington. CRC, a method adapted from biology, uses repeated sampling from distinct sources—in this case, a cold weather shelter (CWS) and a homeless outreach program called Neighbor to Neighbor (N2N)—to estimate the total homeless population, including those missed by direct counts. The study found that CRC estimated 115 homeless individuals (95% CI [93, 137]) over four months in winter 2021–2022, nearly double the 61 individuals counted in the single-day PIT count conducted the same year. The findings suggest that CRC can supplement PIT counts, especially in rural areas, by providing a more comprehensive and dynamic understanding of homelessness, though both methods have inherent assumptions and limitations.