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The YouGov discrepancy: just how badly is LAB doing?

June 29th, 2019

Wikipedia

A clear lead or struggling to be neck-and-neck?

Three parties have dominated the coverage of opinion polling and major elections over the last three months. On one side, the Tories have clearly suffered a catastrophic loss, shedding more than half the support they had at the start of the year, losing more than 1300 councillors and then nearly all their MEPs in May. Against which, the Brexit Party has exploded out of nowhere to win the EP elections and to vie for the lead in Westminster voting intention, while the Lib Dems have dramatically recovered from their near-decade-long slump to gain over 700 councillors, more than double their poll share and win their biggest election since 1910 (London, in the EP vote).

What of the other party in the apparent four-way tie for the lead, Labour? Perhaps because their slump in support began earlier (early March, following the TIG defections), and hasn’t been quite so precipitous, it’s not been so well-observed either.

But just how big has that drop been? Here we arrive at a polling quandary. Present-day polling gives a disproportionate prominence to YouGov, who release far more polls than anyone else. This is unfortunate since their results are quite out of line with other pollsters.

For example, these are the average poll scores from YouGov so far this month:

Brx 24.3
LD 20.5
Lab 19.8
Con 19.3
Grn 9.0

Whereas the average shares from all other pollsters combined (and the relative difference against YouGov) is:

Lab 26.0 (+6.2)
Con 23.8 (+4.5)
Bxt 19.0 (-5.3)
LD 18.0 (-2.5)
Grn 6.2 (-2.8)

These are, clearly, starkly different splits. At the extreme, YouGov shows Labour 4.5% behind the Brexit Party, while other firms have them 7% ahead. Before anyone gets too excited about the implication for seats won implied in any individual poll, let’s remember that someone’s methodology for producing the underlying polling data is very wrong (never mind the methodology for translating the votes into seats – though that’s a discussion for another day).

In as far as we have anything to go on, the chances are that it’s YouGov which is out. At the EP elections, their final poll underreported Con and Lab against the actual results by 2% and 1% respectively, and substantially overstated the Brexit Party (by some 6%), which is very much in line with their Westminster findings compared to other companies (with the possible exception of Opinium).

For Labour, it may be cold comfort that they’re probably polling in first place with a mid-twenties share rather than in third, behind the Lib Dems and perhaps sub-20. After all, for the main opposition party to be in the mid-20s in any circumstance is extremely poor but it’s still not quite the existential crisis that not being the largest left-of-centre party is. Note also the much larger share that YouGov give to the Greens: almost half the Labour share, rather than less than a quarter of it that the other companies find.

Of course, these figures were before Labour casually revived media attention of their antisemitism problem by readmitting an unrepentant Chris Williamson into their party while the EHRC inquiry into it is still ongoing. That, plus the internal Labour criticism to it, might trigger a decline in Labour’s vote share after a month of relative stability, as might well the election of the new Tory and Lib Dem leaders – and goodness knows what might happen after the summer, when the Brexit drama reaches a new climax. Even if Labour is ahead now, there’s no guarantee it’ll last.

David Herdson