GE2015: Polling Problems vs. Information Seeking Biases
By my bedtime on the night of the last UK General Election, May 7 2015, one thing, at least, was clear. No matter who won, the pollsters lost. This is what makes the possibility of the Social Election Project so exciting – the flaws of traditional polling. Leading up to the election, the polls showed the Conservative Party and the Labour Party neck in neck; yet, the Tories went on to win handily. What in the world happened with the polls? In contrast, the Social Election Prediction Project focuses on predicting elections from online information seeking behavior such as search trends, a source with its own set of biases. How do the the biases of this method compare to the issues with the polls leading up to the election?
Problems with Traditional Polling
First, it is important to note that the polls leading up to GE2015 were not just wrong on the whole; they were wrong in a consensus. All predicted a tie, or close to it, between the two majority parties when the outcome was anything but. Why were the polls are all so biased in similar ways? A few ideas…
…Because the polls report percentages, not seats. Comres, for example, in their final predictions set the Conservatives at 35 percent, Labour at 34 percent and UKIP at 12 percent nationally. Of course, due to the first past the post system, voting percentages do not translate neatly to seats in the House of Commons.
…Because of how the polls ask about specific constituency preference. FiveThirtyEight noted that their model would have been far more accurate if they used a more “generic” question about party preference, as opposed to the question they used regarding preference for candidate in the respondent’s specific constituency.
…Because voters changed their minds. Peter Kellner, the President of the polling firm YouGov insinuated as much in an interview with The Telegraph.
…Because of the effect of earlier polls showing the strength of the SNP. Early polls showed the SNP gaining in strength and as the New York Times noted that later in the election the “Conservatives had adroitly exploited fears among voters that the Labour Party would be able to govern only in coalition with the Scottish National Party.”
…Because of the perennial issue of shy tories? Long a known factor in UK polling, more people will vote Conservative than will declare such to a pollster.
…Because of the way the poll participants were recruited? Poll respondents are representative by age, sex and social class, but as The Guardian notes, there still might be other divides between people who will respond to an online and telephone poll and those that will not.
…Because of the results of the other polls. Market research firm Survation noted that their final poll predicted a Conservative victory much in line with the final result but the poll seemed so out of sync with all the others that they declined to published it. This is not the first time in recent memory that UK opinion polling was notably inaccurate. In 1992, opinion polls leading up to the election predicted a Labour victory and yet the Conservatives won handily. A group of pollsters convened an inquiry following the embarrassment of the 1992 election and pinned the problem on: voters switching late in the election, unrepresentativeness in the people polled and shy tories.
Biases in Online Information Seeking
Using information from online information seeking, such as search trends, can remedy some of the above problems. One does not have to adjust for shy tories for example, or the wording of the question as search trend data constitutes demonstrated, not reported, behavior. Furthermore, search trend data would change as a voter considered new options and so could accommodate strategic voting. However, using online information seeking data presents its own issues. While the majority of the UK population uses the Internet, according to the 2013 Oxford Internet Survey, there is still 22 percent of population that does not. These people will not be represented at all in search trends.
Furthermore, of the UK voters that do use the Internet, they may not use our data sources such as Wikipedia, when they are looking for information. Yet the social election prediction project encompasses far more countries than just the UK; the next blog post will discuss how polling practices – and polling reliability – varies around the world.