I wrote about this in my last post – exploring what, if anything, we could tell from the polling about whether Boris Johnson would get the blame if Brexit did indeed end up being delayed past the 31st October.

With the government now pushing for an election in December the issue has now arisen again, with lots of people dragging out a ComRes poll from the 16-17th October that asked how people would vote in an election if Britain had NOT left the European Union on 31st October, showing Labour one point ahead. Some people are sharing it with excitement, others with dismay. Both should probably calm themselves.

As a general rule, you can only usefully ask people a polling question if they actually know the answer… and most of us aren’t actually very good at predicting how we will respond to hypothetical situations. If you take this specific question, it was asking people to imagine quite a lot. How had the delay come about? Had the government fought it, or gone along with it? How had the government explained and reacted to the delay? Given the dates of the fieldwork, many respondents wouldn’t even have known about the deal. All of these things will impact how the public react and whether they blame the Conservatives or not… but were impossible for respondents to know.

In short, polls measure current public opinion. They can’t predict the future. While you can ask respondents to predict their own future opinions, they aren’t necessarily very good at it.


The position in the polls remains much the same as the last time I updated – the Conservatives still have a substantial lead, though one that varies from pollster to pollster due to methodological differences. The figures also remain somewhat artificial given we know that a major event with the potential to transform the political weather (either Brexit going ahead, or Brexit being delayed) is looming upon the horizon. Perhaps the more interesting question is, therefore, what impact is that likely to have on the polls? Or perhaps more to the point, can polls tell us *anything* useful about what impact it would have on the polls?

Most of the polling that has set foot in this rather difficult territory has attempted to shed some light on what will happen if Boris Johnson ends up seeking a delay to Brexit.

Several polls have asked who people would blame if Brexit ended up being delayed, and as a rule they’ve tended to show that people wouldn’t blame Boris Johnson or, at least, that he would not be widely blamed by Conservative supporters or Brexiteers – the voters he needs to keep hold of. YouGov found 39% of people think a delay would be Boris Johnson’s fault to a large or moderate extent, 46% think it would bear little or none of the fault. Among Leave voters only 18% thought Johnson would bear significant blame. A ComRes poll found 34% think Johnson would bear much responsibility for a delay, 33% some responsibility and 22% no responsibility at all. Among leave voters only 19% thought he would bear much responsibility, 35% some, 37% none.

However, polls that have asked how people would vote if there was an election after a further delay to Brexit have invariably shown the Conservative party losing support and the Brexit party gaining it (for example, this ComRes poll from last month). A naive reading of that might be these two approaches are contradictory (the ones asking about blame suggest most people wouldn’t blame Boris, the ones asking hypothetical voting intention imply he would pay a heavy cost) – in reality they don’t. Even if most of his supporters wouldn’t blame Boris Johnson for an extension, if 1 in 5 Tories voters blamed him enough to defect to the Brexit party it severely damage the Conservatives’ electoral hopes.

I would urge some degree of caution on both these approaches though. We are asking people to imagine a rather vague hypothetical situation. A delay in Brexit could cover all sorts of different scenarios. Maybe Boris Johnson will apply for an extension, maybe he’ll resign and someone else will. Maybe he’d have done it willingly, maybe he’d have been forced into it by the Courts. More recently it’s been floated that he could even end up seeking an technical extension in order to deliver a deal. People’s reactions may be extremely different depending on the different circumstances. For now these uncertainties should put a question mark over any polls asking hypothetical questions about how the public think they would react to a delay – if political circumstances become clearer in the next week then perhaps, just perhaps, we’ll be in a better position to do useful polling on the issue.

In the meantime we are left to speculate. The questions I ask myself when trying to predict what the impact on public opinion are these. Can I imagine Boris Johnson seeking an extension and it NOT damaging him? Well, in certain circumstances I suppose I can, yes. On the other hand, can I imagine Boris Johnson having to seek an extension and it NOT giving Nigel Farage a boost?


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There have been three polls over the last week – in the Sunday papers there were polls from ComRes and Opinium, the regular YouGov poll for the Times last week. Voting intention figures were:

Opinium – CON 37%, LAB 25%, LDEM 16%, BREX 13%, GRN 2% (tabs)
ComRes – CON 28%, LAB 27%, LDEM 20%, BREX 13%, GRN 5% (tabs)
YouGov – CON 32%, LAB 23%, LDEM 19%, BREX 14%, GRN 7% (tabs)

There isn’t really a consistent trend to report here – YouGov and ComRes have the Conservatives declining a little from the peak of the Johnson honeymoon, but Opinium show them continuing to increase in support. My view remains that voting intention probably isn’t a particularly useful measure to look at when we know political events are looming that are likely to have a huge impact. Whatever the position is now, it is likely to be transformed by whether or not we end up leaving the European Union next month, on what terms and under what circumstances.

What did receive some comment was the sheer contrast between the reported leads, particularly because the ComRes (1 point Tory lead) and Opinium (12 point Tory lead) were published on the same day.

Mark Pickup, Will Jennings and Rob Ford wrote a good article earlier this month looking at the house effects of different pollsters. As you may expect if you’ve been watching recent polls, ComRes tend to show some of the largest Labour leads, YouGov some of the biggest Tory leads. Compared to the industry average Opinium actually tend to be slightly better for Labour and slightly worse for the Tories, though I suspect that may be changing: “House effects” for pollsters are not set in stone and can change over time, partly because pollsters change methods, partly because the impact of methodological differences change over time.

What that doesn’t tell us why there is a difference. I saw various people pointing at the issue of turnout, and how pollsters model likelihood to vote. I would urge some caution there – in the 2017 election, most of the difference between polls was indeed down to how polling companies predicted likelihood to vote, and this was the biggest cause of polling error. However when those new turnout models backfired and went wrong, polling companies dropped them. There are no longer any companies using demographic based turnout models that have a huge impact on voting intention figures and weight down young people. These days almost everyone has gone back to basing their turnout models primarily on how likely respondents themselves say they are to vote, a filter that typically only has a modest impact. It may be one factor, but it certainly wasn’t the cause of the difference between ComRes and Opinium.

While polling companies don’t have radically different turnout models, it is true to say (as Harry does here) that ComRes tends to imply a higher level of turnout among young people that Opinium. One thing that is contributing to that in the latest poll is that Opinium ask respondents if they are registered to vote, and only include those people who are, reducing the proportion of young people in their final figures. I expect, however, that some of it is also down to the respondents themselves, and how representative they are – in other words, because of the sample and weights ComRes may simply have young people who say they are more likely to vote than the young people Opinium have.

As regular readers will know, one important difference between polling companies at the moment appears to be the treatment of past vote weighting, and how polling companies account for false recall. Every polling company except for Ipsos MORI and NCPolitics use past vote in their weighting scheme. We know how Britain actually voted at the last election (CON 43%, LAB 41%, LDEM 8%), so a properly representative sample should have, among those people who voted, 43% people who voted Tory, 41% people who voted Labour, 8% who voted Lib Dem. If a polling company finds their sample has, for example, too many people who voted Tory at the previous election, they can weight those people down to make it representative. This is simple enough, apart from the fact that people are not necessarily very good at accurately reporting how they voted. Over time their answers diverge from reality – people who didn’t vote claim they did, people forget, people say they voted for the party they wish they’d voted for, and so on. We know this for certain because of panel studies – experiments where pollsters ask people how they voted after an election, record it, then go back and ask the same people a few years later and see if their answers have changed.

Currently it appears that people are becoming less likely to remember (or report) having voted Labour in 2017. There’s an example that YouGov ran recently here. YouGov took a sample of people whose votes they had recorded in 2017 and asked them again how they had voted. In 2017 41% of those people told YouGov’s they’d voted Labour, when re-asked in 2019 only 33% of them said they had voted Labour. This causes a big problem for past vote weighting, how can you weight by it, if people don’t report it accurately? If a fifth of your Labour voters do not accurately report that they voted Labour and the pollster weights the remaining Labour voters up to the “correct” level they would end up with too many past Labour voters, as they’d have 41% past Labour voters who admitted it, plus an unknown amount of past Labour voters who did not.

There are several ways of addressing this issue. One is for polling companies to collect the data on how their panellists voted as soon as possible after the election, while it is fresh in their minds, and then use that contemporaneous data to weight future polls by. This is the approach YouGov and Opinium use. The other approach is to try and estimate the level of false recall and adjust for it – this is what Kantar have done, instead of weighting to the actual vote shares in 2017, they assume a level of false recall and weight to a larger Conservative lead than actually happened. A third approach is to assume there is no false recall and weight to the actual figures – one that I think currently risks overstating Labour support. Finally, there is the approach that Ipsos MORI have always taken – assuming that false recall is such an intractable problem that it cannot be solved, and not weighting by past vote at all.

Dealing with false recall is probably one reason for the present difference between pollsters. Polling companies who are accounting for false recall or using methods that get round the problem are showing bigger Tory leads than those who do not. It is, however, probably not enough to explain all the difference. Neither, should we assume that the variation between pollsters is all down to those differences that are easy to see and compare in the published tables. Much of it is probably also down to the interaction of different weighting variables, or to the very samples themselves. As Pat Sturgis, the chair of the 2015 enquiry into polling error, observed at the weekend there’s also the issue of the quality of the online panels the pollsters use – something that is almost impossible to objectively measure. While we are wondering about the impact of weights and turnout filters, the difference may just be down to some pollsters having better quality, more representative panels than others.


Prorogation polling

Three polling companies – YouGov, Ipsos MORI and Survation – have so far released polling on the government’s decision to prorogue Parliament in mid-September.

YouGov polled on the issue twice – a snap poll on the day of the announcement itself, with the same question repeated overnight. The on-the-day figures were 27% acceptable, 47% unacceptable, 26% don’t know. The follow-up poll had a similar split, but with the number of don’t knows dropping off as people became aware of the story – 31% said it was acceptable, 53% unacceptable, 16% don’t know. Tabs are here)

Ipsos MORI did an unusual online poll (almost alone among pollsters these days, most of their polling is done by phone). They found 30% thought the decision to prorogue Parliament was right, 46% thought it was wrong. Tables are here.

Finally there was a Survation poll for today’s Daily Mail. This found a closer result, with the public fairly evenly split – 39% were supportive, 40% opposed (note this is rounding the totals for support/oppose after they’ve been summed, hence the apparent discrepancy with the tables). Tables are here.

Overall it looks as if the public are opposed to the prorogation decision – though it is unclear to what degree. Whether that really matters or will make any dent in the government’s support is a different matter. Opposition to prorogation is concentrated among Remainers (in YouGov 82% of Remainers think the move is unacceptable, but only 24% of Leavers, in MORI’s poll 74% of Remainers think it was wrong, only 20% of Leavers, in Survation 74% Remainers, 14% leavers). If most of the opposition to the move comes from people who are opposed to the government’s policy anyway (and I expect the more fervent opposition comes from those who were most fervently opposed already) the government are hardly likely to worry too much over losing the crucial “people who hated us anyway” vote.

Both YouGov and Survation included voting intention in their surveys:

YouGov’s topline figures were CON 33%(-1), LAB 22%(nc), LDEM 21%(+4), BREX 12%(-1), GRN 7%(-1)
Survation’s topline figures were CON 31%(+3), LAB 24%(nc), LD 21%(nc), BREX 14%(-2), GRN 3%(nc)

Changes in the YouGov poll are from a poll earlier this week, before the announcement. In Survation changes are from a poll three weeks ago. There is a little movement up and down, but certainly nothing that suggests the announcement has done immediate damage to Conservative support.


A very quick update on voting intention polls over the last few weeks. As usual August is a relatively quiet period – opinion pollsters have holidays too. The fact that we have a new Prime Minister hasn’t made much change to that. In August so far we’ve had five voting intention polls:

BMG/Independent (Dates TBC) – CON 31%, LAB 25%, LDEM 19%, BREX 12%, GRN ?
ComRes/Telegraph (11th Aug) – CON 31%, LAB 27%, LDEM 16%, BREX 16%, GRN 4% (tabs)
Survation (11th Aug) – CON 28%, LAB 24%, LDEM 21%, BREX 15%, GRN 3% (tabs)
Opinium/Observer (9th Aug) – CON 31%, LAB 28%, LDEM 13%, BREX 16%, GRN 5% (tabs)
YouGov/Times (6th Aug) – CON 31%, LAB 22%, LDEM 21%, BREX 14%, GRN 7% (tabs)

Note that the BMG tables aren’t up yet, hence I don’t know the level of support for the Greens or their fieldwork dates. These polls continue to show the boost in Conservative party support following Boris Johnson’s accession filtering though. It is the first “Post-Johnson” poll for BMG and Survation, and they show the Conservatives up by 3 and 5 points respectively. We’re now at a point where the most recent polls from all the regular polling companies show the Conservatives back ahead, though the size of their lead differs given the variation in figures between pollsters.

Normally I would be speculating about how long the government’s honeymoon boost would last. It’s not really the case here given how many political events are going to be crammed into the next few months. Events will likely preempt its natural unwinding: whatever diplomatic negotiations or stand offs occur between the government and the EU (starting with the G7 meeting this week), whatever Parliamentary moves there may be against the government or against No Deal, the party conferences, whatever preparations or announcements there may be on No Deal and, of course, the actual outcome at the end of October. The current levels of party support seem rather irrelevant in the face of that – the Conservatives are probably happy to have a lead at the moment, but there are ten weeks ahead of us that are packed with events that can throw everything up in the air.