Revised 2019 Homeless Count Data Summaries

Published July 22, 2020 | Last updated July 30, 2020 | 8,621 total views

Below please find adjustments to the numbers reported last year in the 2019 Greater Los Angeles Homeless Count at the Los Angeles City Council District and County Supervisorial District levels.

The adjustment reflects a methodological update provided by LAHSA’s statistical partner, University of Southern California (USC), used to estimate the number of unsheltered adults in 2019 at the CD and SD levels.

The 2019 method used a locally derived multiplier that has a wider, less precise confidence interval for estimating the number of inhabitants in a vehicle or structure. A different multiplier was used for each council district, but because not all districts had the same number of surveys, the precision of the estimates varied widely.

The 2020 method replaces that with a regionally derived multiplier that achieves a narrower, more precise confidence interval. This means that each council district’s multiplier was derived from the SPA or SPAs that comprise it.

This change does not affect the overall homeless count or the counts for SPA levels. It does change the 2019 City of Los Angeles total, which remains within the previous year’s margin of error. Accordingly, it also affects the percent changes from 2018 to 2019 and from 2019 to 2020.

Based on the Greater Los Angeles Homeless Count, LAHSA supplies numbers at the county, Continuum of Care, and Service Provision Area level to help policy makers direct our approach to ending homelessness. Count estimates within political boundaries such as individual cities, legislative districts, and tracts are released to the public but are not used in funding decisions. Swings between neighborhoods vary widely due to movements in enforcement and cleanups. The SPA level is the most reliable view of geographic changes.

LAHSA uses a well-established methodology for determining the total homeless population for each neighborhood.

The first step is to gather the number of individuals and families observed by the 7,000+ volunteers who canvassed every street in the Los Angeles Continuum of Care (CoC) during the “Street Count.” They also recorded on tally sheets how many “dwellings” they saw, which includes cars, vans, RVs, tents and makeshift shelters (CVRTM). Because volunteers were asked to keep a respectful distance from anyone experiencing homelessness, they were not able to see how many people were living inside the dwellings.

The second step is then to make this determination of how many people were in the dwellings.

A “multiplier” for each type of dwelling is statistically derived by the results of approximately 4,000 demographic surveys conducted across the CoC. These surveys ask respondents where they sleep at night and if others were also living with them at that time. The multipliers are calculated annually by LAHSA’s statistical consultants at USC because they change from year to year.
Once they are derived, the sum for each type of dwelling found on all the tally sheets for each city is multiplied by this factor.

The third step is adding in the unsheltered number found by “special teams.” These are made up of LAHSA street outreach teams and other trained professionals from local homelessness service providers who were assigned to check out difficult-to-reach areas such as along riverbeds. Their tally sheets were then included with those completed by the community volunteers.

Frequently Asked Questions

Does this mean that last year’s City Council numbers are unreliable?
Our statistical methods produce lower margins of error at larger geographic boundaries. The statistical methods used for the homeless count produce the most useful figures at the County, CoC and SPA levels. These are compiled from the PIT count, the demographic survey, and the youth count. Numbers for local jurisdictions are provided as a courtesy, but are typically not used for policy and funding decisions.

Why is the City of Los Angeles number changing?
The city number is compiled from the total of the 15 city council districts. The new City of Los Angeles number is within the margin of error of the previous figure.

Isn’t the Point-In-Time count a one-to-one census? Why would that change so much?
The PIT count is a census of individuals as well as vehicles and structures. A multiplier must be used to estimate the number of people living in structures and vehicles. By deriving the multiplier from a wider range, USC believes it has established a more precise calculation with a more narrow confidence interval.

Are last year’s figures in error?
The calculation used last year was valid but less precise. The revised method improves the precision of the estimates.

What was wrong with last year’s multiplier?
Last year’s multipliers were less precise. Last year, the team chose to derive each council district's multiplier from surveys collected in that district. This has the benefit of “locally sourced” information that may reveal more about the district in question. However, some districts had fewer surveys to draw from than others. By using multipliers drawn from a larger area, we lose some of that “local sourcing” but draw our multiplier from a broader data set and, we believe, ultimately arrive a more precise estimate.

What about 2018’s figures? Why aren’t they changed?
Previous to 2019, a constant multiplier was used to estimate the number of people in vehicles and structures. The district-by-district method used in 2019 allowed us to report standard errors for those estimates for the first time. The 2020 count improves further on that method by deriving multipliers from each SPA, preserving local specificity but improving the confidence interval.

View USC's methodology report here and their multipliers and estimates overview here.

2019 Greater Los Angeles Homeless Count—City of Los Angeles