Need to Know | 27th November 2014

How much attention should we pay to daily polls?

How much attention should you pay to the polls? This week Labour have led […]

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How much attention should you pay to the polls? This week Labour have led comfortably, then drifted down, and now the Tories “lead”, according to YouGov’s overnight tracking poll.

This is – as some have pointed out – noise. The trend is what is worth watching, along with the results of each polling house, rather than just one. Reporting on the polls throughout the week relies on following the YouGov/Sun tracking poll, published from Monday through Thursday night.

But they are only one of the eight major, active British pollsters. We hear from some of them – ICM, Ipsos Mori – only once a month, or others – ComRes, Survation, Opinium – only every few weeks. Aside from YouGov, only two other pollsters poll weekly: Ashcroft, who often creates a mini-news cycle on Monday afternoon, and Populus, who poll on Monday and Friday mornings.

If you pay attention to YouGov’s daily tracker polls you can write a new headline almost every day. The real story is the trend across all eight pollsters over time. May2015‘s Poll of Polls is keeping a track of all the numbers each day. We like to keep an eye on our rolling four-day average:

If we just looked at the daily averages, we see a more muddled picture – especially in mid-week, when just YouGov are polling.

Daily polls become important over time. Or they can mean something if a number of pollsters show the same sudden shift, as Ashcroft, Populus and YouGov did on Monday, when all three put Labour ahead by at least 4 points. But that seems to have been about a post-Rochester Tory-to-Ukip swing, rather than any lasting change; Labour’s vote share never really changed, and the Tories have now “recovered”, at least in YouGov’s numbers.

Polls are truly informative over months and years.

And while a four-day average is at least something of a trend, polls are truly informative over months and years, rather than days and weeks. Exploring the polls over the last 44 years – as you can do here on May2015, focusing in on any week or month since August 1970 – tells the story of post-1960s British political history.

Click through to track the rise and fall of the SNP, who led the polls for three months in late 1981, or the Blair and Brown years, and the Tories’ long, slow, limited recovery since 1997.