Which polls were most accurate in 2010

President Michael Dimock explains why. The vast majority of U. Use this tool to compare the groups on some key topics and their demographics. About Pew Research Center Pew Research Center is a nonpartisan fact tank that informs the public about the issues, attitudes and trends shaping the world. It conducts public opinion polling, demographic research, media content analysis and other empirical social science research.

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Are you a Faith and Flag Conservative? House races are more error-prone than gubernatorial or U. Senate polls, which in turn are more error-prone than presidential election polls. This is important to remember once you start seeing polls of House races later this year. This is a lot of words to spend without addressing the question of how the polls performed in Polling the primaries is hard — the average polling error in all presidential primaries since is 8.

Because voting in general elections operates along increasingly predictable demographic lines , pollsters can use demographic weighting to make up for other problems in their samples.

Polling in the primaries could be a pretty wild ride. Polling of the presidential general election is the trickiest case to evaluate. The average error was 4. However, the error was about average as compared to the long-term accuracy of presidential polls. Our presidential election model gave Trump a much better chance than other forecasts did , in part because it derived its probabilities based on polls from elections dating back to not just since Below are the error calculations for polls of presidential elections dating back to On average since , polls in the final 21 days of presidential elections have missed the actual margins in those races by 4.

That error was concentrated much more in state polls, which missed by an average of 5. The gap in was larger than usual, however. At the national level, these errors somewhat canceled each other out, but not so much at the state level.

But even the state polling errors were well within the normal range. Their 5. Two other factors undoubtedly contributed to the widespread criticism about how polls performed in One is that people had gotten spoiled by recent presidential elections. The other factor is that the error was more consequential in than it was in past years, since Trump narrowly won a lot of states where Clinton was narrowly ahead in the polls. National polls were actually a bit more accurate in than in That accuracy rate was just 71 percent in the presidential election, however.

Down-ballot polls — House, Senate and gubernatorial — also had a bad year. But this is definitely not how FiveThirtyEight recommends evaluating pollster accuracy. Despite relatively strong showings in pre-election state polls by the eventual president, Clinton was generally shown to be the leader, and this, combined with the electoral history of the states, led most observers including, apparently, the Clinton campaign to assume that the vote from these states would fall dutifully in line for the Democrat and Clinton would take her assumed place as the nations first female Chief Executive.

Had he not, Secretary Clinton would have won, and the polls would have been vindicated. So what of the exit polls from these three states? If we were to see evidence of real polling incompetence, we should find it there, especially given that the total Trump margin of victory for these states was a razor thin 77, votes, averaging.

Nuff said, right? Not quite. As it happens, the margin of victory for Clinton predicted in each of these states was, in fact, within margin-of-error of the actual result. Despite the fact that the wrong winner was predicted, the polling results were right! The problem, as it happens, lies not in our polls but in ourselves. Taking factors such as margins-of-error into consideration, which we must, and considering the miniscule deviations from this margin discussed above, rather than hiding their heads in shame, pollsters should proudly proclaim the amazing accuracy of their results in the context of one of the most confounding presidential elections ever.