Polls are certainly helpful for understanding the mood of the electorate. But they’re not helpful if you don’t understand how to read polls, or if you rely on unreliable polls. A good poll that actually represents a diverse nation tends to be from a random sample and needs to have a rigorous methodology.

So, with that in mind, has Trump won “every poll” taken on the second presidential debate?

The Facts

We checked with Scott Clement, polling manager at The Washington Post. He cited four polls that have been completed on the debate between Trump and Hillary Clinton at Washington University in St. Louis on Oct. 9.

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Clement said that the best-quality post-debate poll so far was CNN’s immediate post-debate survey, which was conducted by calling back respondents to its previous national telephone survey who said they would watch the debate. That survey was conducted among a national random sample of cellular and landline phones, so it has the best claim of representativeness.

The result? Fifty-seven percent in that poll said Clinton won, while 34 percent said Trump won.

Clement noted that the sample was more Democratic, as this group was more likely to have watched the debate, but the partisan balance was not so far different from the general public.

Another debate-night survey was done by YouGov, which relies on opt-in Internet panels to recruit respondents and is not based on a random sample of the public. This kind of poll is viewed with suspicion by many in the polling community, but YouGov’s method has produced reasonably accurate pre-election surveys in the past.

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The result? Clinton got 47 percent; Trump got 42 percent. So a narrow victory for Clinton.

There was also a Morning Consult-Politico poll, which also uses an opt-in panel that weights the sample by demographics, though it is a newcomer and does not have a track record of pre-election estimates like YouGov.

The result? Forty-two percent said Clinton won, while 28 percent said Trump won.

The result? Forty-four percent said Clinton won, while 34 percent said Trump won.

So four polls, of varying quality but certainly respectable, all show that Clinton won. So what is Trump talking about? This tweet gives the answer.

These polls are all “garbage polls,” as our colleague Philip Bump calls them. These are Internet polls that did not attempt to recruit a representative sample of the country and are open to anyone, even people in Russia. All you need is an Internet connection. So they are representative of nothing, not even enthusiasm.

The Pinocchio Test

Trump claims “every poll” shows that he won the second debate “in a landslide.” In reality, not a single quality poll shows he won the debate, though one indicated a near-tie. In review, the results are:

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CNN: Clinton 57 percent; Trump 34 percent

YouGov: Clinton 47 percent; Trump 42 percent

Morning Consult-Politico: Clinton 42 percent; Trump 28 percent

NBC-SurveyMonkey: Clinton 44 percent; Trump 34 percent

So Trump earns Four Pinocchios — or as Clement puts it, Four Pollocchios.

Four Pinocchios

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