Weight, Weight, Weight

No, Kantar did not imply young people will have an historically low turnout in the upcoming General Election.

It was suggested, in a Novara Media newsletter and elsewhere, that a recent Kantar poll that “the turnout for each demographic… would be the lowest in decades”, with the exception of people aged over 65.

This article looks at what survey weights are, correct mistakes in the Novara Media newsletter, and shows the problem that Kantar are seeking to solve.

Why weight?

What are survey weights?

A polling company or research organisation conducts a survey. The goal of a survey is to be representative of its intended population, such as all adults in Great Britain or the United Kingdom. Surveys aim to take a perfect ‘slice’ of the general public: generally asking one or two thousand people what their views are. Using these surveys, we can get good estimates of important parameters — like what proportion of people intend to vote for each party.

These responses are then adjusted so the samples look more like the overall population. If we know that they are more women in the population than there are in the sample, we ‘weight’ the responses of women, so they count for more. Companies will often use variables like age and gender for these weightings.