I mean, if you're looking for sub-1% accuracy, you're not going to get it, but polls are usually accurate to within a few percent. In the US, the last couple of elections were quite close, so fairly small misses had a big impact (at least in 2016; in 2020 the only state that was clearly a wrong call based on polls was Florida, and arguably Georgia).
Notably, polls were generally fairly accurate for the US 2018 midterms.
In general, polls work better in electoral systems where national polls are useful; the US presidential election in particular is challenging.
This does not imply polls are more or less accurate than prediction markets.
The way to measure that is to look at 100 cases where prediction markets predict 75% odds. If approximately 75 of them result in a winner, prediction markets are accurate.
Looking at a single data point and declaring a probabilistic predictor to be inaccurate is not even wrong.
That's pretty much how all polling works and it's surprisingly accurate when done well. If your sample reflects the general population 1500 can be more than enough to get a really good picture.
There are unavoidable, expected, sampling errors which are, by definition, random. That's why valid, trusted polls calculate a confidence interval instead of a single discrete result.
Other types of "errors" -- election results that repeatedly fall outside the confidence interval, or are consistently on only one side of the mean -- only arise when the poll is flawed for some reason. Maybe you relied on landlines only, maybe you spoke with too many men, or too many young people, asked bad questions, miscalculated "likely voter," whatever. Accurate, valid, trusted polls don't have these flaws, the ONLY errors are small, random, expected sampling errors.
Which polls were so far in error? The presidential vote polls were ~2% out and I think most in this thread on this topic will concede a 2% error either way.
Did you do any research at all on this? The polls were within a few points of the popular vote, and state polls were well within typical polling errors consistent with ... the entire history of polling.
This is exactly why you should never blindly trust a single poll.
We don't know who is right/wrong until after the election so it is better to assume that a range of different polls taken at different times with different methodologies is likely to be more accurate.
Election polls are almost always right for the only ultimate answer that matters: who is going to win[0]. They also accurately predict the margin of victory. Same link. Polls, in general, are typically measuring tendencies or preferences, which they also (tend to) accurately capture. So saying they are always wrong doesn’t really make sense, as they are not trying to be right in an absolute sense. The error is with the reader who misconstrues what the poll is measuring and how it is doing so.
Some of the commentary on HN has been about how polls are especially bad now because of the types of people who actually respond to them. But the article shows that presidential polls have been historically "bad".
"[N]ational polls will miss by about 3 percentage points in an average year ... That means the margin of error is closer to 7 or 8 points. And every presidential election so far this century has fallen within that range."
I think people just have unrealistic expectations of how accurate polls can be.
No. The polls were fairly accurate; the problem was how people used the polls. This is also a topic that's been beaten to death over the last two years.
Why isn't anyone considering that within the margin of error, the polls were correct? Isn't the confidence interval +/- a few percentage points anyways??
I really have no idea where this idea that the polls failed comes from. There were only two bad calls this cycle and every other outcome was within the margin of error. It was pretty much the same case in 2016 where people who had no idea what they were talking about suddenly decided they were certain polling failed because they are unable to grasp the concept of margin of error and sample size.
Polls can only guess about turnout and the try to work backwards from there. The turnout estimates were wrong but not shockingly so, and as a consequence a lot of polls ended up having the result be at the far end of their margin of error. Nothing went wrong. Polling is hard. Get over this idea that you can have some sort of certainty regarding an election until we actually hold the election.
Notably, polls were generally fairly accurate for the US 2018 midterms.
In general, polls work better in electoral systems where national polls are useful; the US presidential election in particular is challenging.
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