What is an opinion poll?

An opinion poll is a survey in which canvassers ask a representative sample of people the same questions. The opinion poll aims to find out what people think about a theme or issue. It is a market research technique in which polling companies ask people about their opinions.

Organizations use opinion polls during election campaigns to determine which party is most likely to win. In fact, there are political polls even when there is no election campaign.

We also call an opinion poll a Gallup poll. We name Gallup polls after George Gallup (1901-1984), an American statistician who was a pioneer in sampling techniques.

Mr. Gallup and Claude E. Robinson founded the advertising research company Gallup and Robinson Inc. in 1948. It later became the Gallup Organization.

According to CollinsDictionary.com:

“An opinion poll involves asking people’s opinions on a particular subject, especially one concerning politics.”

Opinion poll – a scientific survey

What makes an opinion poll scientific? There are two features to ‘scientific’ opinion polls:

– A research company chooses the respondents.

– The company has gathered sufficient information about the respondents. In other words, the data in the results match the profile of the survey group.

For example, let’s suppose that thirty percent of the target population is over 55. The polling company must, therefore, ensure that the sample population has the same proportion of people aged 55+.

Opinion poll - image with explanation and examples
An opinion poll represents the opinions of a population. Researchers conduct a series of questions to people in a sample population. The surveyors ask respondents questions face-to-face, through the telephone, or via the Internet.

Opinion poll accuracy

Opinion polls never claim to be one-hundred percent accurate. Put simply; none of them can perfectly reflect opinions in the whole population.

Imagine that nationally, people’s opinions regarding the death penalty are split fifty-fifty. In other words, 50% are for, and 50% are against the death penalty.

According to statistical theory, in a random poll of one-thousand individuals, the survey will be 100% accurate 19 times out of 20. Therefore, the opinion poll is accurate to within three percent. In other words, it has a 3% margin of error.

However, to be accurate within three percent, you must have a 100% response rate. That is, all the people in the randomly-selected population responded.

If fewer than 100% of people in a survey respond, then its accuracy will be inferior.

With a sample of 2,000 respondents, the poll will have a 2% margin of error – with a 19 times out of 20 accuracy. Also, only if 100% of the people in the sample population respond.

Over the past few years, opinion polls have become worse at predicting election or referendum results.

Most polls predicted that Britons would choose to remain in the European Union. However, in a 2016 referendum, 52% of British voters chose Brexit. Brexit stands for BRitain EXITing the European Union.

Most opinion polls also got the 2016 American presidential elections wrong. They predicted that Hillary Clinton would win. However, Donald Trump won.

Video – Opinion polls

This Open University video explains how an opinion poll works.