… Candidates who are losing an election will always attack the polls as flawed, or worse, and some voters will take their word for it. Polling might never be free of “correlated errors” — where pollsters make the same mistake in multiple states, causing one party to be underestimated across the nation. And artifacts of random chance — such as polls that underestimate Republicans in three of the past four elections — can easily be mistaken for partisan bias.
The best course of action: Do not expect perfection from the polls. Survey research is hard. Pollsters have to contact people who do not want to talk to them, talk about extremely personal, high-stakes issues and make a complex series of statistical decisions before presenting the public with something as unlikely as a consensus set of opinions. No person can perfectly navigate these obstacles all the time. CONTINUED
David Byler, Washington Post