Last year the election polls got it wrong. Since then most pollsters have made only minor interim changes – ComRes, BMG and YouGov have conducted the biggest overhauls, many others have made only tweaks, and all the companies have said they are continuing to look at further potential changes in the light of the polling review. In light of that I’ve seen many people assume that until changes are complete many polls probably still overestimate Labour support. While on the face of it that makes sense, I’m not sure it’s true.

The reason the polls were wrong in 2015 seems to be the samples were wrong. That’s sometimes crudely described as samples including too many Labour voters and too few Conservative voters. This is correct in one sense, but is perhaps describing the symptom rather than the cause. The truth is, as ever, rather more complicated. Since the polls got it wrong back in 1992 almost all the pollsters have weighted their samples politically (using how people voted at the last election) to try and ensure they don’t contain too many Labour people or too few Conservative people. Up until 2015 this broadly worked.

The pre-election polls were weighted to contain the correct number of people who voted Labour in 2010 and voted Conservative in 2010. The 2015 polls accurately reflected the political make up of Britain in terms how people voted at the previous election, what it got wrong it how they voted at the forthcoming election. Logically, therefore, what the polls got wrong was not the people who stuck with the same party, but the proportions of people who changed their vote between the 2010 and 2015 elections. There were too many people who said they’d vote Labour in 2015 but didn’t in 2010, too many people who voted Tory in 2010 but said they wouldn’t in 2015, and so on.

The reason for this is up for debate. My view is that it’s due to poll samples containing people who are too interested in politics, other evidence has suggested it is people who are too easy to reach (these two explanations could easily be the same thing!). The point of this post isn’t to have that debate, it’s to ask what it tells us about how accurate the polls are now.

The day after an election how you voted at the previous election is an extremely strong predictor of how you’d vote in an election the next day. If you voted Conservative on Thursday, you’d probably do so again on Friday given the chance. Over time events happen and people change their minds and their voting intention; how you voted last time becomes a weaker and weaker predictor. You also get five years of deaths and five years of new voters entering the electorate, who may or may not vote.

Political weighting is the reason why the polls in Summer 2015 all suddenly showed solid Conservative leads when the same polls had shown the parties neck-and-neck a few months earlier, it was just the switch to weighting to May 2015 recalled vote**. In the last Parliament, polls were probably also pretty much right early in the Parliament when people’s 2010 vote correlated well with their current support, but as the Lib Dems collapsed and UKIP rose, scattering and taking support from different parties and in different proportions polls must have gradually become less accurate, ending with the faulty polls of May 2015.

What does it tell us about the polls now? Well, it means while many polling companies haven’t made huge changes since the election yet, current polls are probably pretty accurate in terms of party support, simply because it is early in the Parliament and party support does not appear to have changed vastly since the election. At this point in time, weighting samples by how people voted in 2015 will probably be enough to produce samples that are pretty representative of the British public.

Equally, it doesn’t automatically follow that we will see the Conservative party surge into a bigger lead as polling companies do make changes, though it does largely depend on the approach different pollsters take (methodology changes to sampling may not make much difference until there are changes in party support, methodology changes to turnout filters or weighting may make a more immediate change).

Hopefully it means that polls will be broadly accurate for the party political elections in May, the Scottish Parliament, Welsh Assembly and London Mayoral elections (people obviously can and do vote differently in those elections to Westminster elections, but there will be a strong correlation to how they voted just a year before). The EU referendum is more of a challenge given it doesn’t correlate so closely to general election voting and will rely upon how well pollsters’ samples represent the British electorate. As the Parliament rolls on, we will obviously have to hope that the changes the pollsters do end up making keep polls accurate all the way through.

(**The only company that doesn’t weight politically is Ipsos MORI. Quite how MORI’s polls shifted from neck-and-neck in May 2015 to Tory leads afterwards I do not know. They have made only a relatively minor methodological change in their turnout filter. Looking at the data tables, it appears to be something to do with the sampling – ICM, ComRes and MORI all sample by dialing random telephone numbers, but the raw data they get before weighting it is strikingly different. Looking at the average across the last six surveys the raw samples that ComRes and ICM get before they weight their data has an equal number of people saying they voted Labour in 2015 and saying they voted Tory in 2015. MORI’s raw data has four percent more people saying they’d voted Conservative than saying they’d voted Labour, so a much less skewed raw sample. Perhaps MORI have done something clever with their quotas or their script, but it’s clearly working.)


It’s been almost two months since we’ve had any polling on the London mayoral race, but Opinium have released a new poll today showing Sadiq Khan still ahead. First round preferences are Khan 31%, Goldsmith 26%, Whittle 2%, Berry 2%, Pidgeon 2%, Galloway <1% (these figures are including don't knows, hence the low scores. Without don't knows it would work out at Khan 48%, Goldsmith 42%, Berry, Whittle and Pidgeon all on 3% and Galloway on 1%.)

Given the low level of support for all the candidates outside the main two Khan is close to winning on the first round anyway, but after asking a forced choice and reallocating preferences between the final two it works out at Khan 55%, Goldsmith 45%. Full tabs are here.


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YouGov have released some fresh EU polling, a batch of five new polls conducted in the last two weeks. The most recent poll, conducted on Wednesday and Thursday, has topline figures of Remain 40%, Leave 37% and the three polls before that also showed Remain with a small lead. While YouGov have been typically showing a very tight race, their 2016 polls up to now have shown small leads for LEAVE, so four YouGov polls in a row showing REMAIN ahead suggests some movement. It will be interesting to see if that is reflected in other polling, and whether movement continues in that direction.

Note that this isn’t the start of daily EU referendum polling. We put the EU question on lots of polls in a row because it was the control question for an academic experiment. There will NOT be YouGov daily referendum polls for the next four months!

Tabs should be up in the YouGov archive later on today.


Earlier this week there was a new YouGov poll of Conservative party members in the Times or, more specifically, two new polls of Conservative party members: YouGov polled the same party members before and after Boris Johnson came out in favour of leaving the EU to see what impact it had on the leadership race. Results are here.

At the simplest level Boris was ahead before, and was ahead afterwards, but there were some interesting shifts. Boris’s approval rating among Conservative party members dropped significantly after he came out (from 83% approval to 76% approval), but his position in the leadership race improved. Presumably he annoyed some members who saw his actions as disloyal or disagreed with his stance, but he consolidated the support from those who did not.

Almost unavoidably Boris coming out was going to upset some members – he has carefully avoided having many fixed political opinions over the years, so I expect many pro-European members would have assumed Boris agreed with them, many anti-EU members would have assumed Boris agreed with them. For once, he is forced off the fence and forced to upset some people – so his overall approval rating among Tory party members fell. However, in the race to be the next Tory leader his position has improved. 43% now say they’d back Boris, up from 38%, with support falling for Theresa May and Sajid Javid, both of whom were seen as potential “outers” and both of whom ended up supporting Remain. Asked how they’d vote in a match up between Osborne & Boris the figures don’t change as much (Boris 55%, George 36% before, Boris 56%, George 38% after) – the broader balance between those party members who want Osborne as the next leader and those who don’t hasn’t changed much, it’s just Boris is now more clearly the “not-George” candidate.

Only a quarter of Tory party members said that the leadership candidates’s stances on the EU were an important factor in picking the next leader – 4% said they wanted the next leader to be someone who had campaigned for the UK to stay, 20% wanted the next leader to be someone who campaigned to leave, three-quarters picked other criteria as their main considerations. Far and away the most widely picked criteria was someone who will make a competent PM, picked by 67%, followed by someone who has a good chance of winning the next election on 52%.

At the moment, Boris is very clearly the front runner if he reaches the stage of the membership vote. At the moment that looks relatively likely – there will be a fair chunk of Conservative MPs who will want to vote for a leadership candidate who supported leaving the EU, and Boris is now obviously the biggest “pro-Leave” beast in the Tory party (though it will be interesting to see how the Parliamentary party divides – Boris maybe anti-EU, but he is not otherwise associated with the Tory right. Will the right of the parliamentary party fall in behind him, or will they want their own “proper” standard bearer?).

That said, it is very early days. If the referendum is lost it’s possible Cameron could go soon, but if not he may be here for a few years yet. Among Conservative party members there is very little call for Cameron to make an early departure – only 20% think he should step down in 2016 or 2017 (roughly the same proportion as think he should change his mind and teste the next election – the majority think he should stay till at least 2019). In reality though, any pressure for Cameron to go early will come from the Parliamentary party, not from the rank-and-file membership, and I expect that will depend upon the extent to which the Tory party rips itself apart over the next three months and the final result of the referendum.


There were two new polls on the Scottish Parliament elections today – a new TNS face-to-face poll and a new Survation online poll. Note that while they are both newly published the different methodologies mean that the Survation fieldwork is far newer than TNS’s – Survation polled over the weekend, TNS polled over the last three weeks. Topline figures are below:

Survation
Constituency vote: SNP 54%, LAB 21%, CON 16%, LDEM 5%
Regional vote: SNP 43%, LAB 19%, CON 14%, LDEM 7%, GRN 9%, UKIP 6%

TNS:
Constituency vote: SNP 60%, LAB 21%, CON 13%, LDEM 4%
Regional vote: SNP 55%, LAB 21%, CON 13%, LDEM 4%, GRN 6%

Both polls have a huge SNP lead and their victory in May seems a foregone conclusion. Labour are comfortably in second place – the last round of Scottish Parliament polling from TNS showed the gap between Labour and the Conservatives narrowing, but that has faded away again. The Survation poll has UKIP up at 6%, which has provoked some comment – it appears to be something to do with Survation’s methodology rather than a new development, looking back over past Scottish Parliament polling Survation have consistently had UKIP at 5-6% in the Holyrood regional vote while other companies consistently give them between 1-3%. John Curtice has speculated that this may be something to do with the question wording Survation use, which refers to the regional vote as a “second vote” and might lead to some people giving a second preference (this would also explain the big gap they fond between SNP constituency and regional vote). A couple of years ago Roger Scully did an experiment looking at different wordings in Welsh Assembly polling, and found you got really different answers depending on whether the question said “second vote” or “regional vote”, so it is plausible that there’s a similar effect in Scotland.