As a census surveyer during the pandemic, I can say that questionnaires are pursued pretty relentlessly, at least in Canada. There will always be some people that refuse or can't be surveyed for some reason, but it's about as accurate as a human to human data collection process can be. The public only has access to somewhat lower resolution data, which probably nullifies the necessity of accounting for every single person anyway.
In some cases, especially with volatile/vulnerable populations living in apartments and what not, we'd revisit the same residence at least 3 times if we don't get it done the first time.
The less than 20% number in some neighborhoods seems like it'd be possible, especially if it's very dangerous, but unlikely, though I don't know the U.S system.
In some cases, especially with volatile/vulnerable populations living in apartments and what not, we'd revisit the same residence at least 3 times if we don't get it done the first time.
The less than 20% number in some neighborhoods seems like it'd be possible, especially if it's very dangerous, but unlikely, though I don't know the U.S system.