A 68-seat Johnson majority: do YouGov’s startling election figures make sense?

This is not a sentence I ever expected to write; but I have some sympathy for Dominic Cummings. Boris Johnson’s notorious adviser is worried that too many people will take a Conservative victory for granted, stop worrying about Jeremy Corbyn becoming prime minister, and hence fail to vote Conservative on 12^th December. Might complacency and the desire of many lukewarm Tories on a dark, cold and possibly wet December evening to stay at home, cost Johnson his premiership?

Cummings is right to be concerned. The evidence is stacking up that the Conservatives are on course for a clear, and possibly large, majority; but their lead is not impregnable. Like a soccer club two goals up with ten minutes to go, victory is very likely but not yet certain.

Today’s Times brings Cummings no relief. YouGov has questioned 100,000 people. It projects a complacency-inducing 68-seat majority for the Conservatives, who are ahead in 359 seats. Labour is down to 211—just two more than in their catastrophic defeat under Michael Foot in 1983. The SNP is up to 43, while the Lib Dems, with 13, are up just one since 2017—their four expected gains are offset by three projected losses.

Do YouGov’s figures make sense? My large answer is yes; but I have some reservations about particular seats, which I shall discuss below. (Non-interest declared: I left YouGov in 2016 and have had no involvement in the developments of the techniques it has used to make these projections.)

What YouGov has done is employ a method known as MRP (“multilevel regression post-stratification,” since you ask) to estimate party support in each constituency—not so much by recording what voters in those seats say (there are too few, even in a sample as large as this) but by lining up the demographic profile of each constituency with the voting intentions of people like that in similar seats.

This method allowed YouGov to warn the Tories two years ago that they might lose apparently safe seats such as Canterbury and Kensington—while telling Labour that it was in trouble in traditionally heartland seats such as Walsall North and Mansfield. YouGov’s data was not always right: for example, it understated the surge to Labour in a range of Remain-voting seats in London. But the big picture was right, and YouGov deserved the credit it received for its MRP analysis.

I am sure the big picture is right again. Labour risks losing dozens of marginal seats, especially in Leave-voting areas in the north and midlands. The Tories look like gaining seats they have not won for decades, if ever, such as Bishop Auckland, Bassetlaw, Wrexham and even Bolsover, which Dennis Skinner has held for almost half a century.

YouGov is also right to show Conservative support holding up in most of the party’s Scottish seats, and Jo Swinson’s failure to lead a Lib Dem surge. Both these factors are helping the Tories’ overall majority to edge up.

Now to my reservations. When MRP produces figures for a given constituency, it is telling us what is likely to happen in this kind of seat, not necessarily this particular seat. It cannot take account of factors that matter to specific constituencies: particular issues, the popularity of specific candidates, the reputation of the local council, the effectiveness of local campaigning, possible tactical voting, and so on.

In some seats, specific Deltapoll constituency surveys (which I have organised, and reported for the Observer) vary from YouGov’s MRP projections. For example, Deltapoll shows Luciana Berger to be the clear challenger to the Tories in Finchley and Golders Green, well ahead of Labour, while YouGov shows her only narrowly ahead of Labour’s candidate. However, this seat has the highest share of Jews of any UK constituency—and YouGov’s model does not separate out Jewish voters. Berger was, of course, a Labour MP who rejected her former party’s anti-semitism. YouGov’s figures seem to understate her specific appeal.

The same may be true for Sam Gyimah and Chuka Umunna in Kensington and the Cities of London and Westminster. Deltapoll’s local surveys show these two high profile, strongly pro-Remain converts to the Lib Dems have a good chance of winning—if enough Labour supporters vote tactically and switch to them.

On the other hand, YouGov may be understating the support for Greg Hands, the incumbent Conservative who backed Remain in 2016, in Chelsea and Fulham. Deltapoll’s local data shows this former minister holding on to the Tory Remain vote, which is significant in his patch, better than Conservatives elsewhere.

In other places, there are questions rather than outright doubts. Has YouGov captured the huge effort at Brunel University to register all students to vote in the local seat—Uxbridge, where Johnson himself is defending the relatively modest majority of 5,000? In Dagenham, has this MRP exercise taken account of the latest demographic changes which might save Labour’s Jon Cruddas from the defeat that YouGov projects? Might Caroline Flint benefit from her strong support for Brexit, giving her a chance of defying the projection of a Tory lead in Don Valley, a seat that Labour has held continuously since 1922?

All that said, whatever errors there are in projections to specific seats do not invalidate the broad picture painted by YouGov. For Johnson to be deprived of an overall majority, there will have to be strong tactical voting, which did not happen much in 2017—and also big voter movements around Britain in the final fortnight of this campaign, which emphatically did.