If I recall correctly, this source was criticized because their measurement for being "out of state" was that you haven't been in CA for 2 years or so. So if someone had come in 2+ years ago for the CA homeless benefits then they would be considered not out of state.
I say supposedly because it doesn't mention how they got that information. If they used county records, it's a very different trust paradigm than if they just asked.
EDIT: I might be thinking of a different study, because going to that link shows that 65% were in LA county for 20 years supposedly: https://www.lahsa.org/documents?id=2059-2018-greater-los-ang...
I say supposedly because it doesn't mention how they got that information. If they used county records, it's a very different trust paradigm than if they just asked.