Self-selecting surveys and sample sizes

The size of a self-selecting sample is often unimportant.

Richard Tice, the Reform party leader, asserted on Twitter:

FASCINATING: huge poll, totally at odds with YouGov ( Govt propaganda arm) that says 71% favour them. Is YouGov so discredited it’s better to believe the opposite of many of their polls?

The cited YouGov survey had a different subject (nightclubs) and wording:

Would you support or oppose people being required to show they have received both doses of the Covid-19 vaccine as a condition of entry into nightclubs?

To reiterate: self-selecting surveys are not reliable ways to measure public opinion.

A self-selecting survey means respondents choose whether to take part. They put themselves into the sample. There are many examples, including text-in ‘polls’ and clickable website surveys. Social media sites may allow their users to generate a survey, which others can vote in.

We can make no inferences from self-selecting surveys to the general population.

There are many statistical issues with these surveys, including self-selection bias. People who see a…