YouGov Distorts its Latest Election Poll to Get Headlines

With the longest British election campaign in full swing, the pollsters are getting more attention than usual. It is disappointing, then, to see a major polling company falling into bad statistical habits.

Certainty

YouGov has conducted a poll of 1800 people that reverses the Conservative lead of a few days ago, which itself reversed Labour’s lead from the previous poll. You might think that the random seeming changes in results separated by only a few days might, indeed, be random sampling errors, but YouGov is happy to imply otherwise with its headline “Labour Lead at 4%”. That headline has been repeated, without any caveats, by The Sunday Times with a banner headline of “Labour races into 4-point lead after Miliband’s TV success”. But it isn’t true.