Political polling has been an inherent part of democratic societies for long, and these snapshots guide campaign strategies, media coverage, and voter expectations. One question frequently asked is how accurate the political polls are. Knowing what affects the accuracy of political polls is thus important to understand their results.
The Science of Polling
Political polling is essentially a science. There are various methodologies applied by pollsters to ensure samples that largely reflect the population. This includes random sampling, where each and every person in the concerned population has an equal probability of selection. A CalTech report describes a sample of 1,000 to 1,500 as large enough to determine general sentiment around the United States. Another tool applied by pollsters is a technique known as weighting, which ensures that the sample is representative demographically: age, gender, race, education level, and so on.
Challenges to Accuracy
Yet, even using this scientific approach, a number of complications may render political polling less than accurate:
Sampling Error: Even in random sampling, there is a margin of error. The larger the sample size, the smaller the margin of error will be, and vice-versa. Many polls boast very small margins of error; however, this number generally includes just one source of potential error. In fact, several other sources of potential error may affect these polls, such as sampling bias, question wording, or nonresponse bias.
Nonresponse Bias: The risk of nonresponse bias grows as the response rates to the polls go down. If there are any groups that are less likely to respond, their views may be underrepresented in the results.
Question Wording and Order: Many times, the wording of questions and sometimes even their order skews the respondents’ answers. While the pollsters strive to frame neutral questions, subtle biases can still creep in.
Timing: Polls are snapshots of a particular point in time. If anything, public opinion does change quite fast, owing to many key events or rising information. There may not be any validity in predicting the election outcome based on polls taken long before the event occurred.
Turnout Predictions: Perhaps the most exacting task of all is that of accurately predicting who is going to vote. It is often the case that a poll needs to predict voter turnout and then infer from the respondents who among them are likely to vote—a task that sometimes proves very challenging in close contests or from populations with low historical turnout.
Efforts to Improve Accuracy
Pollsters are continually trying to improve their methods. Advances in technology and data analytics open new routes for reducing errors. Online panels and mixed-mode surveys—a mix of phone, online, and in-person interviews—are increasingly used. Moreover, pollsters are at work on new ways to adjust for nonresponse bias and on better turnout predictions.
While political polling is a very important tool for understanding the pulse of public opinion, it certainly is not infallible. It is very important to know the intrinsic limitations and factors that influence its accuracy while trying to interpret poll results. Because methods for conducting polls are ever-changing, ways of strengthening accuracy and reliability are highly sought after. Voters and analysts alike should critically approach the polling data—both its value and its limitations.
