There's ambiguity between the formal classification of homelessness as used by the city and organizations, and other connotations such as the street homeless. People across the spectrum seem to abuse this and similar terminological ambiguity to suit their particular argument or rhetorical point.
There's also the fact that self-reporting regarding things like previous residence, drug use, etc is unreliable. I've always found it odd that some people on HN are so credulous of these numbers even though in other contexts they'd be the first to point out that self-reported data makes bad science.
This doesn't mean the numbers are wrong, just that we should have very large error bars which grow as we make inferences. If we combine ambiguity regarding homelessness with an already substantial number like 35%, and tack on issues like mental illness, it's hardly a stretch to say that drug use and mental illness are the principle problems for the seeming intractability of street homeless reduction.
There's also the fact that self-reporting regarding things like previous residence, drug use, etc is unreliable. I've always found it odd that some people on HN are so credulous of these numbers even though in other contexts they'd be the first to point out that self-reported data makes bad science.
This doesn't mean the numbers are wrong, just that we should have very large error bars which grow as we make inferences. If we combine ambiguity regarding homelessness with an already substantial number like 35%, and tack on issues like mental illness, it's hardly a stretch to say that drug use and mental illness are the principle problems for the seeming intractability of street homeless reduction.