Polling Observatory campaign report #4: Unexpected but not unusual twists and turns in the campaign polls

DipticBy The Polling Observatory (Robert FordWill JenningsMark Pickup and Christopher Wlezien). You can read more posts by The Polling Observatory here.


This post is part of a long-running series (dating to before the 2010 election) that reports on the state of the parties as measured by vote intention polls. By pooling together all the available polling evidence we can reduce the impact of the random variation each individual survey inevitably produces. Most of the short term advances and setbacks in party polling fortunes are nothing more than random noise; the underlying trends – in which we are interested and which best assess the parties’ standings – are relatively stable and little influenced by day-to-day events. Further details of the method we use to build our estimates can be found here and here.

The general election is now just two days away, after a campaign that has defied pundits’ expectations of a walkover for Theresa May’s Conservatives, and seen both surprises and tragic events along the way. While the pollsters will likely deliver their final verdict on what voters are saying tomorrow, the Polling Observatory brings you its final roundup of the polls – as they stood up to Sunday night. We may yet see a late swing from the voters, as the choice between the parties becomes clearer in their minds. As such, our estimates remain ‘a snapshot, and not a prediction’.

In the main, there has been little change from the trends that we reported last week: the Conservatives retain a substantial lead in the polls, though are down from 44.5% to 43.8%, while Labour’s resurgence continues – now on 36.8%, up from 35.5% last week. Consequently, what was a 9-point gap (averaged across the pollsters) is now a 7-point gap. However, the change is within the error of most polls and there is considerable variation in the size of leads that pollsters are showing – in part due to the different turnout adjustments being applied. Based on the range of pollsters’ headline figures, the projected results include anything between a hung parliament and a Conservative landslide, hardly providing clarity on matters. Meanwhile, the Liberal Democrats, UKIP and Greens continue to endure a miserable campaign. Current trends suggest that the big two parties will be more politically dominant in this election than at any time for a generation.

UK 04-06-17 anchor on average

The upturn in Labour’s support has led some to suggest this is the biggest shift in the polls during an election campaign since 1945. It is not entirely without precedent, though. In 2010, the surge in Liberal Democrat support following Nick Clegg’s highly effective performance on the first ever television debate – “Cleggmania” – was of similar scale to Labour’s gains in the polls in the 2017 election (around 10-points). That shift in the polls occurred over the course of just seven days, whereas during this campaign Labour’s poll numbers have risen steadily over a six week period. Some of the Liberal Democrats’ gains in the polls after the 2010 debate dissipated in the subsequent weeks of the campaign, and most of the remaining effects vanished by the time people voted. This is shown below, where the blue, red and yellow markers indicate the actual election result for each of the parties in 2010 – with the orange line notably ending well above the orange circle indicating the result. In contrast, the trends in party support during the 2017 campaign have been more gradual – with no sharp upticks or downticks for either the Conservatives or Labour. This may suggest there is less risk of pollsters’ overshooting in measuring the Labour surge, but only time will tell whether this is the case.

2010

2017

It is also possible to verify this claim historically based on the observed variance in all polls conducted over the campaign. For this, we use 574 polls conducted during the last thirty days of the campaign, for all elections between 1959 and 2017. The results are shown in the table below. What is striking from this analysis is that the variance of Labour’s poll numbers has been high by historical standards, but is still less volatile than the Liberal Democrats’ polling in 2010, 1983 or February 1974 or Labour’s polling in 2001 or 1983. The mean variance in the polls across the three parties is also not that much above the historical average (5.6 compared to 4.9). While 2017 has been a surprising and eventful campaign, it does not differ that much from past elections in terms of variability of the polls. Indeed, it is apparent from the table that the 2015 campaign was quite anomalous in the stability of the polls, which may be influencing our perceptions of how volatile polls can be during UK elections.

Variance in all polls  
Election Conservatives Labour Liberals/SDP/Liberal Democrats Mean N of polls
1959 3.70 2.89 1.85 2.81 10
1964 1.03 1.34 0.77 1.05 6
1966 0.78 1.32 0.28 0.79 6
1970 4.12 1.50 1.56 2.39 8
1974 (Feb) 4.98 7.07 13.94 8.67 12
1974 (Oct) 4.70 3.92 2.59 3.74 29
1979 11.69 5.73 5.49 7.64 24
1983 4.99 11.13 14.53 10.22 50
1987 2.16 4.31 5.00 3.82 32
1992 2.68 2.39 4.84 3.30 54
1997 4.19 8.80 5.43 6.14 39
2001 3.04 10.86 5.28 6.39 30
2005 4.28 3.17 1.91 3.12 58
2010 5.92 4.91 20.40 10.41 88
2015 2.10 2.29 1.08 1.82 82
2017 5.42 10.08 1.33 5.61 46

Much commentary already seems to be preparing for another polling miss after the experiences of 2015 and 2016. Certainly, with current polling showing Conservative leads ranging from 1% to 12% someone will be substantially wrong (and someone should be right). The lack of consensus in the polls provides an important reminder, though, that surveying the public on their voting intentions is a hard business at the best of times – and this task is made more difficult by the varied geographical picture that may well emerge on election night, with Labour well supported among younger, educated voters in cities and the Conservatives making gains in regions and towns where once ‘working class Tories’ of the 1980s are being drawn to the leadership of Theresa May in the aftermath of the Brexit vote. It is possible that Labour will end up with the highest vote share since 2005 or even 2001, but the lowest number of seats since 1935. In the British “first past the post” system, it is not just how many votes a party gets which counts, but where they are cast. The geography of Labour and Conservative support could be just as important as their overall popularity, but at present it is receiving much less attention.

 

Robert FordWill JenningsMark Pickup and Christopher Wlezien

Polling Observatory campaign report #3: All changed, changed utterly

DipticBy The Polling Observatory (Robert FordWill JenningsMark Pickup and Christopher Wlezien). You can read more posts by The Polling Observatory here.


This post is part of a long-running series (dating to before the 2010 election) that reports on the state of the parties as measured by vote intention polls. By pooling together all the available polling evidence we can reduce the impact of the random variation each individual survey inevitably produces. Most of the short term advances and setbacks in party polling fortunes are nothing more than random noise; the underlying trends – in which we are interested and which best assess the parties’ standings – are relatively stable and little influenced by day-to-day events. Further details of the method we use to build our estimates can be found here and here.

With just over a week to go until the general election, the campaign continues to take surprising twists and turns, not least the jaw-dropping projection of a hung parliament from YouGov for The Times.

When we first reported, shortly after the snap-election was called, the Conservatives held a commanding lead and Labour seemed to be meandering towards electoral oblivion. This remained the scenario at the start of May, though the scale of UKIP’s collapse in the polls was starting to become clear – with the Conservatives seemingly the main beneficiary. Just four weeks on, the change in Britain’s political landscape is remarkable – even if the likely outcome of the election (a decent sized Conservative majority at least) remains much the same. Labour has surged in the polls, now standing at 35.5% (up over eight points from 27.8%), while the Tories have fallen back from their initial bump after May called the election (at a still impressive 44.5%, down from the high of 45.6%). UKIP have continued to lose support at a rapid rate, with our estimates putting them at just 4.0% – less than a third of their vote in the 2015 general election just two years ago. The Liberal Democrats’ have also fallen back to just 7.8% (which would be below their catastrophic performance at the last election). Barring an even larger polling miss than occurred in May 2015, the political landscape of Britain looks like it will be redrawn in unexpected ways. There continue to be good reasons to be cautious about what the polls are currently telling us – due to the wide range of Conservative leads being shown by different polling houses and the possibility that Labour’s votes may stack up in seats in cities among younger and educated voters, where they tend to already hold large majorities, while falling away in marginal seats elsewhere.

 

UK 29-05-17 anchor on average

One of the features of our method is that it enables us to estimate the ‘house effect’ for each polling company for each party, relative to the vote intention figures we expect from the average pollster. That is, it tells us simply whether the reported vote intention for a given pollster is above or below the industry average. This does not indicate ‘accuracy’, since this will only be known on June 9th. It could be, in fact, that pollsters at one end of the extreme or the other are giving a more accurate picture of voters’ intentions. Indeed, in contrast to the 2015 election where there was convergence of the pollsters around the Conservative-Labour margin of zero, the most recent set of polls have shown Conservative leads ranging from as little as 5 points to as high as 14 points – outcomes that would have vastly different results in terms of a parliamentary majority for Theresa May.

In the table below we report the ‘house effects’ towards or against each of the parties for all polling companies who have recently conducted surveys. We, of course, estimate separate effects where the same company uses different modes (i.e. where Survation have fielded polls using both online and telephone surveys). We also (where possible) create ‘new’ polling houses where pollsters have implemented significant changes to their method and weighting procedures, though these are not always easy to date precisely. Nevertheless, the estimates give a picture of which pollsters tend to show higher numbers for which party, and thus are a handy guide for reading the latest polls with a dose of caution.

Our estimates reveal a range of house effects – and some interesting patterns too. It is first of all apparent that ComRes and ICM stand out as tending to report higher numbers for the Conservatives (+1.6 points and +1.4 points respectively) and lower numbers for Labour (-1.6 and -1.4 points). In contrast, ORB, Survation (online) and SurveyMonkey are at the other end of the spectrum — in tending to show support for the Conservatives lower and Labour higher than the industry average. Interestingly, Ipsos MORI and Panelbase show both parties higher – due mainly to their tendency to put UKIP much lower (in the case of Ipsos MORI this is a substantial 4.5 points).

House effects, by pollster

Pollster Mode Turnout filter Con Lab Lib Dems UKIP Green
YouGov Online Self-reported -0.3 (0.2) -1.0 (0.2) +0.9 (0.1) +0.4 (0.2) -0.6 (0.1)
ComRes Online Turnout model +1.6 (0.3) -1.6 (0.3) +1.3 (0.2) -0.6 (0.3) -0.3 (0.1)
Ipsos MORI Telephone Self-reported +1.2 (0.4) +2.0 (0.4) +1.5 (0.2) -4.5 (0.3) -0.3 (0.2)
Survation Online Self-reported -2.2 (0.5) +0.5 (0.5) +0.6 (0.3) +1.0 (0.4) -1.1 (0.2)
Survation Telephone Self-reported 0.0 (0.8) -0.4 (0.8) -0.3 (0.5) -0.9 (0.5) -0.3 (0.3)
Panelbase Online Self-reported +1.2 (0.7) +0.4 (0.7) -0.1 (0.4) -0.9 (0.5) -0.2 (0.3)
Kantar (TNS) Online Turnout model -0.6 (0.6) -3.2 (0.6) +1.4 (0.4) +0.7 (0.4) +1.5 (0.3)
ORB Online Self-reported -1.3 (0.6) +1.7 (0.6) -0.4 (0.4) +1.6 (0.4) +0.2 (0.2)
SurveyMonkey Online Unknown -0.8 (0.7) +0.9 (0.7) -1.9 (0.4) +1.1 (0.5) +1.6 (0.3)
Opinium Online Self-reported +0.1 (0.5) +0.7 (0.5) -0.5 (0.3) +0.4 (0.3) -0.5 (0.2)
ICM Online Turnout model +1.4 (0.3) -1.4 (0.2) +0.3 (0.2) +0.8 (0.2) +0.1 (0.1)

Pollsters have made many methodological changes since 2015, making it tricky to discern the causes of variation in these ‘house effects’. One notable feature of the methodology used by ComRes and ICM is the use of demographic turnout models to predict the propensity of individuals to vote. This has the consequence of down-weighting those respondents who have been less likely to vote in previous elections – giving rise to considerably lower Labour vote shares due to their current reliance on younger respondents and previous non-voters. In contrast, other firms such as Ipsos MORI and Opinium use self-reported likelihood to vote, giving rise to slightly higher vote shares for Labour. We will only know which of these adjustment procedures (if either) has been effective on June 9th, however.

While the Conservatives still hold a sizeable lead, the differences across pollsters could represent the difference between a huge working majority in parliament for Theresa May and an election that delivers few gains to the Conservatives contrary to all expectations.  Only time will tell who has got closest to the result.

 

Robert FordWill JenningsMark Pickup and Christopher Wlezien

Polling Observatory #GE2017 campaign report #2:

DipticBy The Polling Observatory (Robert FordWill JenningsMark Pickup and Christopher Wlezien). You can read more posts by The Polling Observatory here.


This post is part of a long-running series (dating to before the 2010 election) that reports on the state of the parties as measured by vote intention polls. By pooling together all the available polling evidence we can reduce the impact of the random variation each individual survey inevitably produces. Most of the short term advances and setbacks in party polling fortunes are nothing more than random noise; the underlying trends – in which we are interested and which best assess the parties’ standings – are relatively stable and little influenced by day-to-day events. Further details of the method we use to build our estimates can be found here and here.

The Polling Observatory is now able to report on polling from the first fortnight of the election campaign. Our estimates show several notable changes on last time. Firstly, the Conservatives gained nearly three points after announcement of the general election but in the last week this gain has stalled – with their support now standing at around 46%. The big losers in the polls so far are UKIP – who have dropped several points in just the last two weeks (now at 7%). Indeed, their support has almost halved since mid-February, pointing to a bleak electoral outlook for the party. As we noted last time, UKIP’s collapse has closely mirrored the surge in Conservative support. Contrary to expectations, Labour has gained in the polls – with its support now standing at 28%, two points higher than in our last report. In contrast, the Liberal Democrats have fallen back slightly, at 10% still only a couple of points higher than their disastrous performance in 2015.

So far, the polls tell a pretty clear and straightforward story: a towering Conservative lead over their main challengers Labour, the collapse of UKIP and marginal revival of the Liberal Democrats. Whether any surprises lie in wait for us in the next five weeks depends largely upon whether the early Conservative surge wears off at all and whether Corbyn’s Labour can muster further gains in support that would deny Theresa May the landslide that looks on the cards.

UK 01-05-17 anchor on average

 

Robert FordWill JenningsMark Pickup and Christopher Wlezien

Polling Observatory campaign report #1: reading polling tea leaves in the shadow of the bonfire of the experts

DipticBy The Polling Observatory (Robert FordWill JenningsMark Pickup and Christopher Wlezien). You can read more posts by The Polling Observatory here.


This post is part of a long-running series (dating to before the 2010 election) that reports on the state of the parties as measured by vote intention polls. By pooling together all the available polling evidence we can reduce the impact of the random variation each individual survey inevitably produces. Most of the short term advances and setbacks in party polling fortunes are nothing more than random noise; the underlying trends – in which we are interested and which best assess the parties’ standings – are relatively stable and little influenced by day-to-day events. Further details of the method we use to build our estimates can be found here and here.

It has been almost 18 months since the Polling Observatory’s last investigation of the Westminster polls, though the intervening period has seen dramatic political events – Britain’s vote to leave the EU, a change in Prime Minister, and much more besides.

The surprise result of the 2015 general election prompted much reflection on the reliability of polling methodologies – most notably in the report of the official inquiry into the pre-election polls – as did the outcome of the 2016 referendum on Britain’s membership of the EU. The vanquishing of the polls, and election forecasts, has added fuel to the bonfire of the experts. To populists, the unpredictability of voters may serve to further undercut the authority of elites.

While the events of 2015 and 2016 provided a valuable reminder that a dose of caution is needed when digesting the latest polls, they remain the best way of assessing relative shifts in public opinion.

As regular readers will know, we pool all the information that we have from current polling to estimate the underlying trend in public opinion, controlling for random noise in the polls. Our method controls for systematic differences between polling ‘houses’ – the propensity for some pollsters to produce estimates that are higher or lower on average for a particular party than other pollsters. While we can estimate how one pollster systematically differs from another, we have no way of assessing which is closer to the truth (i.e. whether the estimates are ‘biased’). This was where our election forecast came unstuck in 2015, as the final polls systematically over-estimated support for Labour and under-estimated support for the Conservatives.

Because most pollsters have made methodological adjustments since May 2015 – designed to address this over-estimation of Labour support – it is inappropriate to ‘anchor’ our estimates on their record at previous elections. Instead, we anchor our estimates on the average pollster. This means the results presented here are those of a hypothetical pollster that, on average, falls in the middle of the pack. It also means that while our method accounts for the uncertainty due to random fluctuation in the polls and for differences between polling houses, we cannot be sure that there is no systematic bias in the average polling house (i.e., the industry as a whole could be wrong once again).

Our latest analyses are based on polls up to April 18th, the day of the announcement of the general election to be held on June 8th. Since then, a number of polls have suggested an even larger Conservative lead – and it will be interesting to see if this is sustained in coming weeks of the campaign. The Polling Observatory’s headline figures currently put the Conservatives on 43%, far ahead of Labour on 25.7%. The Liberal Democrats at 10.5% have overtaken UKIP, at 9.8%, for the first time since December 2012. Meanwhile the Greens are lagging well behind at 4.3%.

UK 19-04-17 anchor on average

Our estimates also provide insights on the trends in support for the parties since May 2015. Under David Cameron, support for the Conservatives had been slipping, especially in early 2016. It was only immediately following the EU referendum vote, and around the time that Theresa May took over as PM, that they have enjoyed a sharp rise in support. In contrast, Labour’s support has steadily been declining since April 2016 – from around the start of the EU referendum campaign. This is well before ‘the coup’ that some have blamed for Labour’s poor polling. We find no evidence to support those claims here.

While UKIP support rose steadily in the year following the 2015 general election, it slumped after the Brexit vote and has continued to decline since. It is too soon to write off UKIP for good, but it is clear that the party faces an uncertain future, threatened by an emboldened Conservative Party plotting Britain’s course out of the EU. By contrast, Brexit has given a renewed purpose to the Liberal Democrats, whose support has steadily been increasing since June 2016 – though hardly at a dramatic rate. The largely static support for the Greens highlights that Britain’s ‘progressive’ parties face an uphill battle to win back voters.

The trends since Brexit specifically point towards two gradual shifts: UKIP voters switching to the now more pro-Brexit Conservatives (with the blue and purple lines mirroring each other quite closely above), and the Liberal Democrats slowly recovering, seemingly at the expense of Labour who are slowly declining. The parties that appear to have benefited from Brexit are those now seen as the natural issue ‘owners’ of Leave and Remain.

So the two mainstream parties with clear Brexit positions are rising in the polls, while the one without a clear position (Labour) is declining steadily.

During the election campaign we will provide updates on the state of support for the parties. We will also be undertaking analyses of what ‘the fundamentals’ – such as party leader ratings and the state of the economy – tell us about the likely election result. Our aim will be to provide an assessment of election forecasts generated using different methods and data. After the experience of 2015, where the polling miss threw many forecasts off, we believe that this approach of triangulation may bolster confidence in expectations about the likely result – and also illuminate how different modelling choices and assumptions matter.

Robert FordWill JenningsMark Pickup and Christopher Wlezien

Polling Observatory #1: Estimating support for the parties (with some trepidation…)

DipticBy The Polling Observatory (Robert FordWill JenningsMark Pickup and Christopher Wlezien). The homepage of The Polling Observatory can be found here, and you can read more posts by The Polling Observatory here.


This post is part of a long-standing series (dating to before the 2010 election) that reports on the state of the parties as measured by vote intention polls. By pooling together all the available polling evidence we can reduce the impact of the random variation each individual survey inevitably produces. Most of the short term advances and setbacks in party polling fortunes are nothing more than random noise; the underlying trends – in which we are interested and which best assess the parties’ standings – are relatively stable and little influenced by day-to-day events. Further details of the method we use to build our estimates can be found here.

It is now six months since the television headlines rolled at 10am on May 7th, with the exit poll dropping the bombshell that the polls had got it badly wrong. The election forecasters fared little better, including us: even though our vote model had predicted a Conservative lead of 2-3 points, our seat prediction was nowhere close to the majority achieved by David Cameron. It is with a little trepidation then that the Polling Observatory team returns to provide its assessment on the state of public opinion in late 2015.

As regular readers will know, we pool all the information that we have from current polling to estimate the underlying trend in public opinion, controlling for random noise in the polls. Our method controls for systematic differences between pollsters – the propensity for some pollsters to produce estimates that are higher/lower on average for a particular party than other pollsters. While we can estimate how one pollster systematically differs from another, we have no way of assessing which is closer to the truth.

One possibility with this method is to use the result of the last election to ‘anchor’ our estimates of bias in the polls against the last election result. This treats the election result as if it was produced by a pollster with no systematic error. We can then estimate the systematic difference of each pollster with this hypothetical perfect pollster. With this method, for example, if pollster X produces results which are systematically 2 percentage points higher for the Conservatives than what would be produced by this perfect pollster, we would interpret a poll indicating 40% support for the Conservatives from such a pollster as 38% support for the Conservatives. This approach can be useful where there are recurring historical patterns (such as the tendency of the polls to overestimate the Labour vote and underestimate the Conservative vote), and might allow us to control for systematic bias in the polls.

We have chosen, for now, to anchor our estimates on the average pollster. This means the results presented here are those of a hypothetical pollster that, on average, falls in the middle of the pack.[1] We have chosen to use such a middle pollster rather than anchor on the election result because we believe that the inaccuracies/biases revealed in the polls in May will be different from those which may occur in this election cycle.[2] All of the pollsters have been undertaking reviews of their methods following the big polling miss in May, and it is unlikely that the biases in polling will be unaffected by the changes they are gradually introducing. Because of this, we offer our estimates of party support with an important caveat: while our method accounts for the uncertainty due to random fluctuation in the polls and for differences between polling houses, we cannot be sure that there is no systematic bias in the average polling house (i.e., the industry as a whole could be wrong once again). It may be that the polls are collectively right or wrong. It may also be that a pollster producing figures higher or lower than the average is more accurately reflecting the state of support for the parties than their competitors. Our estimates cannot adjudicate on whether figures on the high or the low side for a party better reflect the underlying preference of the electorate. The only test is on Election Day. Fortunately, none of this prevents us from identifying and reporting on the underlying trends over time.

In terms of the overall story, there has been little apparent change in vote preferences since the election in May. This despite the triumphant budget announced by George Osborne, the surprise ascension of Jeremy Corbyn to leader of the Labour Party (and the onslaught on him and his team from outside and inside the party), and the tax credits row that has quickly taken the shine off the government’s honeymoon period. Unlike the last election, there has been no sudden flight of voters from one party to another, as occurred with the collapse of Liberal Democrat support in the first six months after the Coalition government was formed.

Our estimates suggest that Conservative support has slipped slightly since the heady days of May and June, from around 40% to closer to 37% at the start of November. Despite Labour being divided and in some disarray over its direction, it has made slight gains from around 30% to 32%. This upward drift in the polls largely occurred before election of Jeremy Corbyn as Labour leader, so cannot be attributed to a Corbyn effect. Whether these gains will persist as the election nears and PM Corbyn becomes a possibility, is of course open to debate. At present, though, there is no sign of Mr Corbyn’s election having any impact on his party’s overall support. UKIP support has remained steady at around 13%, and the party shows no signs of going away – even with its own internal conflicts following Nigel Farage’s “unresignation” in the summer. Lagging somewhat behind, the Liberal Democrats continue to flat-line at just under 7%. One of the patterns of the last parliament was the stubborn immovability of Liberal Democrat support. New party leader Tim Farron has much work on his hands to win back voters, and so far there are no green shoots for the party in our estimates. Finally, speaking of the Greens, their support appears to have been squeezed since Labour election Jeremy Corbyn – perhaps because voters attracted by their distinct left wing platform now feel more at home in the Labour party. It has fallen around 1.5 points since the summer. Our estimates for all the parties suggest that the electorate is still to make up its mind on both the new government and the fragmented and much changed opposition. But there are some big events on the horizon, in particular the EU referendum, which may yet provide a shock to move political support in one direction or the other.

UK 01-11-15 anchor on average (1)

One of the reasons why the polling miss back in May came as such a shock was that by election eve there was broad consensus among the pollsters about the level of support for the parties (though of course we noted house effects earlier in the campaign). However, in the period since May the polling has been characterised by much more variation in the standing of the parties. This is revealed in the figure above. The size of the confidence intervals for our estimates in the period since the election (an average of 2.3 points) are more than twice those for the 2010-15 election cycle or for the month just before the start of the short campaign (each an average of 1.1 points). This indicates a much higher level of uncertainty about the state of public opinion today. Part of this could be due to a lower volume of polling since May, or more variation in polling methodologies as pollsters take different approaches in response to May’s polling miss. The greater uncertainty may also reflect the much lower frequency of polling since the election – election watchers used to multiple daily polls have now to accept a more meagre diet of one or two polls a week. The greater uncertainty may, however, also reflect something more fundamental: genuine uncertainty, and hence greater volatility, in the minds of the electorate. Voters are faced with an unexpected Conservative majority government and an unfamiliar and polarising opposition leader attracting widely varying reactions in the media and within his own party. In such circumstances many may be genuinely unsure as to their preferences. Only time will tell whether this uncertainty lasts until the next general election. For now, it provides an important reminder of the need to take single poll results with a degree of caution.

 

Robert FordWill JenningsMark Pickup and Christopher Wlezien

 

[1] The average difference between this middle pollster and those pollsters that produce estimates that are systematically higher for a given party is the same as the average difference between this middle pollster and those pollsters that produce estimates that are systematically lower for that same party.

[2] We came to a similar conclusion during the last election cycle when it became apparent that our method of anchoring on the election result was excessively reducing the estimated level of support for the Liberal Democrats.

 

Polling Observatory Latest #GE2015 Forecast: the Conservatives make slight gains, but the likeliest result is deadlock

DipticBy The Polling Observatory (Robert FordWill JenningsMark Pickup and Christopher Wlezien). The homepage of The Polling Observatory can be found here, and you can read more posts by The Polling Observatory here.


As we enter the closing stretch of the campaign, substantial uncertainty remains about the final outcome. Taking out the random noise, the polls are still showing a close race ahead of May 7th. Some have pointed to differences between telephone and internet pollsters, with the former having shown a steady, if slight, Conservative lead all year. Our method allows us to control for systematic differences between polling houses and variation in the ‘poll of polls’ that is due to changes in the mix of pollsters in the field at a given point in time.

The latest Polling Observatory forecast covers all polls completed up until April 30th, and shows support for the two main parties is still in the balance – with Labour on 33.1% and the Conservatives on 34.2% — though the confidence intervals are such that we cannot say for certain that the Conservative lead is greater than zero.

Our vote forecast points to a higher level of support for the Conservatives than two weeks ago, up 1.4 points at 35.0%, with Labour on 32.6%, up 0.1 points. This reflects the squeeze that the “big two” have put on other parties in the final weeks of the campaign. The Conservative lead now stands at 2.4%, but with considerable uncertainty remaining in our forecast.

Forecast 01-05-15

This slight shift in the balance of polling is reflected in our latest seat estimates. The Conservatives’ median estimate rises by six seats, Labour falls by six seats, and the Liberal Democrats fall by four.  This puts the median Conservative seat lead at just two. However, as the confidence intervals attached to our estimates reveal, this projected lead is highly uncertain, a veritable coin-flip, with a 53 per cent chance that the Conservatives will have more seats than Labour. A majority for either is at present very unlikely, e.g., the likelihood of a Conservative majority is tiny (less than 0.2%). Our estimates further reflect the gains made by the SNP in recent polling in Scotland, with the nationalists now forecast to win 54 out of 59 seats north of the border.

Table 1: Seat estimates, with confidence intervals and change on April 15th

Party March 1st estimate April 1st estimate April 15th estimate April 30th estimate
Conservative 265 271 268 274 (+6)

(251,305)

Labour 285 276 278 272 (-6)

(244, 295)

Liberal Democrat 24 27 28 24 (-4)

(18, 29)

UKIP 3 3 3 2 (-1)

(1, 4)

SNP 49 49 49 54 (+5)

(46, 58)

Others 6 6 6 6

(4, 8)

Northern Ireland (not forecast) 18 18 18 18

The Conservatives’ paths to a governing coalition are even more winding than their slight lead in votes and seats. They cannot reach a majority with the backing of the Liberal Democrats (combined 298 seats, 15 short of a majority) or with both the Liberal Democrats and the Northern Irish DUP (combined 306 seats, assuming the DUP once again win 8 seats), or even by adding UKIP to that two party combination (308 seats total). It would be very hard, with this seat outcome, for the Conservatives to sustain a government without some form of acquiescence from the SNP. Things are rather more promising for Labour.  While they cannot reach a majority with the help of the Liberal Democrats (combined 300 seats), they can with SNP.  Whether that happens remains to be seen, of course.

Table 2: Most plausible governing combinations, based on March and April seat forecasts

Party March 1st estimate April 1st estimate April 15th estimate April 30th estimate
Conservatives + Lib Dems + DUP 298 307 305 306
Conservatives + Lib Dems + DUP + UKIP 301 310 308 308
Labour + SNP 334 325 327 326
Labour + Lib Dem 309 303 306 300
Labour + SDLP + Plaid Cymru + Green + Lib Dem 316 310 313 307
Labour + Lib Dem + SNP 358 352 355 354
Labour + SDLP + Plaid Cymru + Green + Lib Dem + SNP 365 359 362 361

Our projected numbers suggest that while the ballots may all have been counted by May 8th, the shape of the new government may be up in the air for some time after.

Update: we have mow updated our forecast with all polls up to the end of Tuesday 5th May, giving the final Polling Observatory forecast for this parliament:

Conservatives 34.5% (32.6, 36.4)

Labour 32.4% (29.7, 35.2)

Liberal Democrats 8.7% (6.9, 10.6)

In terms of seats, this translates into:

Labour 273 (246, 295)

Conservatives 271  (248, 299)

Liberal Democrats 24 (19, 28)

Scottish National Party 55 (49, 59)

Ukip 2 (1, 4)

Other 6 (4, 9)

Robert FordWill JenningsMark Pickup and Christopher Wlezien

Polling Observatory analysis cited in OfCom’s statement on party election broadcasts

DipticBy The Polling Observatory (Robert FordWill JenningsMark Pickup and Christopher Wlezien). The homepage of The Polling Observatory can be found here, and you can read more posts by The Polling Observatory here.


Regular readers of the blog might be interested to know that our Polling Observatory analysis of support for the parties (a joint venture between the Universities of Southampton and Manchester, Simon Fraser University and the University of Texas at Austin) featured today in OfCom’s statement on party election broadcasts. You can read the full OfCom report, ‘Review of Ofcom list of major political parties for elections taking place on 7 May 2015’, here.

Robert FordWill JenningsMark Pickup and Christopher Wlezien