If you’ve followed the issue of homelessness up and down the west coast, from Seattle to Los Angeles, one of the most fundamental disagreements between ordinary people and activists is over the issues of drug abuse and mental illness. Typically, activists arguing for more housing for the homeless are quick to trot out statistics that show only about a third of people on the street suffer from these problems. Meanwhile, shopkeepers and business people who encounter the homeless frequently suggest the percentage with such problems is higher.

When the agency responsible for the point-in-time homeless count in LA County released its findings earlier this year, they seemed to fit with the claims made by activists. Here’s a slide from the presentation given to elected officials:

Obviously if more than two-thirds of the populations you are trying to help do not have substance abuse or mental problems then it’s reasonable to argue that the key issue is a lack of affordable housing. But what if those numbers were reversed? What if two-thirds of respondents had problems that contributed to their inability to maintain a home?

An analysis of the underlying data performed by the LA Times came up with dramatically different results. In fact the results are nearly the opposite of what was presented to officials:

The Los Angeles Homeless Services Authority, which conducts the annual count, narrowly interpreted the data to produce much lower numbers. In its presentation of the results to elected officials earlier this year, the agency said only 29% of the homeless population had either a mental illness or substance abuse disorder and, therefore, 71% “did not have a serious mental illness and/or report substance use disorder.”

The Times, however, found that about 67% had either a mental illness or a substance abuse disorder. Individually, substance abuse affects 46% of those living on the streets — more than three times the rate previously reported — and mental illness, including post-traumatic stress disorder, affects 51% of those living on the streets, according to the analysis…

The findings lend statistical support to the public’s frequent association of mental illness, physical disabilities and substance abuse with homelessness.

In other words, the public isn’t crazy to think there is more going on here than a lack of affordable housing. In fact, the LA Times points out that a study published Sunday by the California Policy Lab at UCLA found even higher numbers for substance abuse and mental illness among the homeless nationwide. This chart represents their findings based upon a review of 64,000 homeless surveys:

Again, these numbers matter because, as the LA Times admits, homeless activists and advocates tend to downplay these realities:

At a time when cities and counties are struggling to respond to a growing number of street encampments, the UCLA study and Times analysis raise questions about whether government officials are taking the right approach and doing enough for people on the street who have little hope of getting into housing anytime soon…

Advocates for homeless people tend to not focus their messaging on mental illness, disabilities or substance abuse out of concern that doing so unfairly stereotypes and stigmatizes those without a home.

Briefing The Times on this year’s homeless point-in-time count prior to its release, Peter Lynn, executive director of the homeless authority, defended the agency’s statistics on homeless people with disabilities and substance abuse issues. He attributed the idea that the numbers should be higher to perception bias.

Like other local and state officials, he has portrayed the homeless population as being much like the wider population of housed Angelenos.

And this isn’t limited to Los Angeles. When the news special “Seattle is Dying” was released earlier this year, people were struck by the number of homeless who were shown suffering from some combination of drug addiction or mental illness. One homeless woman in the film even said that “100 percent” of the people she encountered on the street had a drug problem.

In response, a group of well-heeled non-profits in Seattle hired a PR firm that generated a series of talking points about the issue. Those talking points were then repeated (without attribution) by various experts in various print outlets. One of the main talking points was that only about 35% of the homeless experience mental or substance abuse problems. And because that was true, they argued, “Seattle is Dying” was a misrepresentation of the problem.

I found those claims to be extremely misleading even before these new surveys, but now I’m wondering if Seattle and other cities aren’t all dialing these numbers down in a similar way. LA’s Homeless Services Authority didn’t dispute the Times’ findings but merely said they were using narrower criteria established by “federal guidelines.” Maybe the Seattle Times, the Oregonian, and the San Francisco Chronicle should take a second look at the point-in-time homeless surveys in their regions.

This debate is far from over but it does seem to have shifted in a significant way this week. The next time you read or hear homeless activists or experts claiming that only a third of the homeless have mental health or substance abuse problems, remember there should be a big asterisk on those figures.