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Election polls are 95 percent confident but only 60 percent accurate, UC Berkeley Haas study finds

How confident should you be in election polls? Not nearly as confident as the pollsters claim, according to a new UC Berkeley Haas study.

Most election polls report a 95 percent confidence level. Yet an analysis of 1,400 polls from 11 election cycles found that the outcome lands within the poll's result just 60 percent of the time. And that's for polls just one week before an election -- accuracy drops even more further out.

"If you're confident, based on polling, about how the 2020 election will come out, think again," said UC Berkeley Haas professor Don Moore, who conducted the analysis with former student Aditya Kotak, B.A. '20. "There are a lot of reasons why the actual outcome could be different from the poll, and the way pollsters compute confidence intervals does not take those issues into account."

If one wants a handy rule:

"Perhaps the way we interpret polls as a whole needs to be adjusted, to account for the uncertainty that comes with them," Kotak said. In fact, to be 95 percent confident, polls would need to double the margins of error they report even a week from election day, the analysis concluded.
by fjallstrom on Mon Nov 2nd, 2020 at 09:39:33 AM EST
by Oui on Mon Nov 2nd, 2020 at 09:45:32 AM EST
[ Parent ]
I think that the meaning the author meant to convey is that the margins of error would have to be tighter, i.e. one half of existing MOEs.

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Mon Nov 2nd, 2020 at 03:01:38 PM EST
[ Parent ]
How so?

If polls are less certain then their real margin of error is larger. For example, if TheHill/Harris has Biden at 49 plusminus 2 percent with 95% certainty, then in reality it is closer to 49 plusminus 4 percent with 95% certainty. Or did you mean the other way around, that to get to 49 plusminus 2 percent with 95% certainty they have to increase paricipants until they are at plusminus 1 percent?

by fjallstrom on Mon Nov 2nd, 2020 at 08:35:04 PM EST
[ Parent ]
For polls to be 95% certain the margins of error would have to be tighter than they are if there is only an 80% certainty. The way it is stated in the article is ambiguous, IMO.


"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Tue Nov 3rd, 2020 at 03:59:02 PM EST
[ Parent ]

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