alt Hacker News>Almost all polls are worthless [...] because the decision to respond to the poll is itself a major portion of the signal.
But most polls I see are from professional pollsters like Pew or YouGov? For them, correcting for this is opinion polls 101. That's why you see "representative sample". They're not just randomly polling 1000 people and taking the average. They're adjusting for a bunch of other demographic factors as well.
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And there's no clear way to adjust for the most basic factor that people who vote for one candidate are less likely to say so.
In order to account for that, you need you know how many people who are less likely to respond are voting for that candidate. And then you're back to square one.
This is why professional polls have had a consistent bias over the last few years, as this hidden unobservable factor's effect has gotten stronger and stronger.
I don't see how they can adjust for the type of people not responding to polls unless they can force them to answer.
Then you're mostly looking at those who "try" - but if you look wider you'll see polls used way more often than that (think of the companies entirely built around it, customer satisfaction surveys, Facebook "polls", etc, etc).
Doing a proper poll is expensive and (frankly) most of the time is pretty predictable or you can get 90% of the results with 10% of the effort, and most times you don't actually care about the results because you're building it to get a result you want anyway.
(Interestingly enough elections themselves almost by definition have notable discrepancies to a "true" perfect sampling; but it's usually overcome by the sheer volume.)
No matter how they adjust demographic factors they cannot control for the willingness to respond to polls at all. They are always subsetting this weird population set that shares that strange variable of being willing to spend ten plus uncompensated minutes with a spam call pollster.