All posts by electionsetc

2019 General Election, Forecast updates

The 2018 and 2019 local election results suggested the Conservatives might struggle to get a majority at the next general election

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By Chris Prosser and Stephen Fisher.

Every May local election results are analysed as indicators of the state of the political parties and scrutinised for what they tell might tell us about the outcome of the next general election. That general election is tomorrow. Although a lot has happened in politics since May 2019, and especially since May 2018, it might be worthwhile reminding ourselves of what happened in the local elections then and what those results portend for the outcome this week.

In 2015, when the polls failed to anticipate a Conservative majority, one of the more successful forecasting models was Chris Prosser’s one based on the 2013 and 2014 rounds of local elections. Unlike the polls – which showed the Conservatives and Labour neck and neck – that model forecast a four point Conservative lead in vote share. Using a uniform change projection, the forecast shares predicted a Conservative tally of 296 seats for 2015, short of an overall majority but better than a uniform projection from the final opinion polls and the best of a set of twelve academic forecasting models for that election.

Applying the same method again, the table below shows that both the 2018 and 2019 rounds of local elections point to a clear lead for the Conservatives in a subsequent general election. However, the forecast shares of the vote from both rounds do not suggest a big enough lead for the Conservatives to be sure of an overall majority. On the average of the two set of vote shares, coupled with a uniform change projection (also using last night’s YouGov MrP projected SNP and PC vote shares) points to a very narrow Conservative majority of 8.

Party Forecast share based on 2018 results Forecast share based on 2019 results Average forecast share Standard Error of share forecast Seats forecast
Con 40.8 36 38.4 4 329
Lab 33.8 29 31.4 4 231
LD 13.4 15.4 14.4 4 23
Other 12 19.6 15.8 4 65

The fact that a forecast based on local elections 7 and 19 months ago should be so close to last night’s YouGov MrP projection of Con 339, Lab 231, LD 15 is remarkable. There is just a difference of 10 seats for the Tories and none for Labour.

Given that since the 2018 local elections we’ve had May’s Deal and the first missed Brexit deadline, and since the 2019 local elections we’ve seen Brexit Party and Lib Dem success in the European parliament elections, a new prime minister, a new Brexit withdrawal agreement, and another missed Brexit deadline, it is even more surprising that most opinion polls now do not differ profoundly from what previous local elections suggested would happen.

2019 General Election, Forecast updates

The Party Leadership Model predicts a Conservative overall majority

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By Andreas Murr and Stephen Fisher.

Two years ago Andrew Adonis wrote a piece in Prospect arguing that Labour should ditch Jeremy Corbyn because of the importance of party leadership for electoral success. The piece claimed that “the best leader wins and nothing else matters,” and in Lord Adonis’s view Mr Corbyn is the worst Labour leader since Michael Foot. So, Adonis concluded already in September 2017, that regarding the next election “Corbyn will lose it decisively if he contests it.”

In response to Adonis’ claims many, including Danny Finkelstein, expressed skepticism about the power of leadership and pointed out that it is difficult to properly evaluate the quality of leaders in retrospect. Once we know who won and who lost we have a tendency to convince ourselves that the winner was a better leader than the loser. But there are ways of producing measures of leadership quality prior to elections which have historically been useful for forecasting election outcome.

The Party Leadership Model, was devised by Andreas Murr in the run up to the 2015 general election. It successfully anticipated David Cameron’s victory unlike the vast majority of other forecasts at the time. Murr has elaborated the model further for this election to produce a seats forecast, not just a prediction as to who will emerge as prime minister. His new model forecasts that the Conservatives will win an overall majority this week with 342 seats, and that Labour will win 254 seats.

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2019 General Election, Polling methodology

Why are polls from different pollsters so different?

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By Stephen Fisher and Dan Snow.

On average the polls have had a fairly consistent and comfortable lead for the Conservatives in this general election campaign. However, around that average there are substantial differences between polls. Some suggest the Conservatives might fail to win a big enough lead to secure a majority, while others point to a Tory landslide with a majority over a hundred. What’s going on?

In short, since this is a long and complicated blog, our tentative conclusion is that the big systematic differences between pollsters are due primarily to systematic differences in the kinds of people they have in their samples, even after weighting. Some of the sample profile differences translate straightforwardly into headline differences. For instance, having more 2017 Conservatives in a sample means there will be more 2019 Conservatives. In other areas there are more puzzling findings. Polls vary in the extent to which women are more undecided than men and in the extent to which young adults are less certain to vote, but neither source of variation has the effect on headline figures that we would expect. Nonetheless for most of the aspects of the poll sample profiles we have inspected, it is remarkable the extent to which polls differ primarily between pollsters, with relatively little change over time for each pollster. This suggests that the way different pollsters have been going about collecting responses has yielded systematically different kinds of respondents for different pollsters. With a couple of exceptions, it seems as though it has been the process of data collection rather than post-hoc weighting and adjustment that may be driving pollster differences in this campaign.

As the graph below shows, a large part of the variation between polls is between pollsters. The pollsters have shown a similar pattern of change in the Conservative-Labour lead over time, most with a peak in mid-November and a slight decline since. The headline Conservative-Labour lead – the basis for the swingometer – is the main guide to seat outcomes. So an important question is why pollsters differ systematically in the size of their published Conservative leads.

ConLabLead

In this blog post we use data from the standard tables that pollsters have to publish as part of the requirements of British Polling Council membership. They contain a wealth of information about the profiles of the different survey samples both before and after weighting and adjustment. We collected data from such tables for all polls between the 30th of October (when parliament voted for an early general election) to the 4th of December (just over a week before the end of the campaign). There have been more polls since then but so far as we can tell they do not substantially change the issues we raise here.

Continue reading Why are polls from different pollsters so different? →

2019 General Election, Combined forecast, Forecast updates, GE19 Combined Forecast

Fifth combined forecast for the 2019 general election

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By Stephen Fisher, John Kenny and Rosalind Shorrocks 

Since our update last week there have been several new forecasts, most notably including the YouGov MRP (multilevel regression and post-stratification) model. That was a nowcast rather than a forecast, but the same is true of most of our “forecasts”. More on differences between forecasting models below, along with some observations about intriguing question wording effects for citizen forecasts.

But first, overall, the seats projections overall have tightened for the Conservatives, who are down from a 353 average last week to 346 this week, while Labour are up from 209 to 218. The Liberal Democrat forecast total has dropped yet again (from 23 to 19). Now they are estimated to return fewer MPs than they had going into the election (20), but still more than the number of seats they won in 2017 (12).

Seats Betting Markets Complex models Simple models Average
Con 343 347 348 346
Lab 220 218 217 218
LD 19 18 19 19
Brexit 0 0 0
Green 1 1 1 1
SNP 45 45 44 45
PC 5 4 3 4
Con majority 36 45 46 42

Conservative Seats - 4th December

There is now remarkably little difference between the betting markets, complex and simple models in the expected size of the Conservative majority. Particularly striking is that on average the complex models differ by only a seat for each party from the simple uniform change projections based on the average of the opinion polls.

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2019 General Election, Forecast updates, GE19 Combined Forecast

Fourth combined forecast for the 2019 general election

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By Stephen Fisher, John Kenny and Rosalind Shorrocks 

There has not been much change in our combined forecast over the last week. The Conservatives are still apparently headed towards a comfortable majority (55 on average) based on an average forecast vote share lead over Labour of 12 points. The average predicted probability of a Tory majority has crept up to 72%, partly due to increasing confidence in the betting markets and the quantitative forecasting models, as well as the polls. Citizens remain much more sceptical. Concerns that the Liberal Democrats might make little advance continue, and were compounded by the Datapraxis MrP forecast of just 14 seats for the party. Otherwise the Datapraxis forecast was largely in line with other forecasts of headline seats totals. Further MrP based forecasts are due this week, including YouGov’s.

Seats Betting Markets Complex models Simple models Average
Con 346 353 360 353
Lab 210 212 204 209
LD 25 21 22 23
Brexit 0 0 0
Green 1 1 1 1
SNP 45 45 43 44
PC 4 4 4 4
Con majority 42 55 69 55

Conservative Seats - 27th November   Continue reading Fourth combined forecast for the 2019 general election →

2019 General Election, Combined forecast, Forecast updates, GE19 Combined Forecast

Third combined forecast for the 2019 general election

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By Stephen Fisher, John Kenny and Rosalind Shorrocks 

Once again all three sources of seat forecasts suggest the Conservatives are heading to a comfortable majority, while Labour are on course for a result on par with their previous post-war low of 209 seats in 1983. The Liberal Democrat forecast has been dropping steadily, so that they are now expected to end up with only a few more MPs than the twenty they had when they chose to support the election.

Seats Betting Markets Complex models Simple models Average
Con 346 354 363 354
Lab 209 211 200 206
LD 30 22 22 25
Brexit 0 0 0
Green 2 1 1 1
SNP 46 46 44 45
PC 4 4 4 4
Con majority 42 58 75 58

Con seats 20 NovLib Dem seats 20 Nov 

Continue reading Third combined forecast for the 2019 general election →

2017 General Election, Combined forecast

How did the election forecasts do in 2017?

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By Stephen Fisher, Rosalind Shorrocks and John Kenny.

Lots of the forecasts for the 2017 British general election were wrong in pointing to a Conservative majority. Most even suggested an increased majority when the party actually lost one. The well-known exceptions are the exit poll and YouGov multilevel regression and post-stratification (MRP) model. Less commonly remembered are the polls that were within a point of the Conservative-Labour lead and so, by standard uniform change calculations, provided an indication that the Tory majority was in jeopardy.

During the election campaign we ran an exercise combining the different forecasts for shares of the vote, seat tallies, and probabilities of a Conservative majority. Inevitably the combined forecast is only as good as the average of what goes into it, and that average was poor. But since the exercise involved classifying and averaging forecasts by the methodology they used, it is possible to reflect on which types of forecasting method performed better than others.

The figure below shows predictions of the Conservative share of the vote over the course of the campaign from the Political Studies Association (PSA) expert survey, betting markets, forecasting models and opinion polls. Strictly speaking polls are snapshots not forecasts, but the final polls performed as well as the experts and better than all the other methods. Consistently the worst source of predictions for the Tory share were the betting markets.

Conservative Vote Share 2017Note: Due to an error in our 2ndJune 2017 betting market calculation (and no way of correcting it at this stage) the betting market line runs direct (interpolates) from 26thMay to the final 8thJune 2017 estimate.

Continue reading How did the election forecasts do in 2017? →

2019 General Election, Combined forecast, Forecast updates, GE19 Combined Forecast

Second combined forecast for the 2019 general election

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By Stephen Fisher, John Kenny and Rosalind Shorrocks

There are still just a few different forecasts for the general election. Perhaps the big changes during the 2017 campaign have made people more hesitant about predicting early this time. Perhaps the problems of the polls in 2015, 2016 and 2017 have put some off the idea entirely. (More on this in our post-mortem for the 2017 combined forecast which we’re still working on.) Nonetheless, this is the second of our weekly blogs where we review the different forecasts from different methods and combine them into an overall forecast.

Here we aggregate seats and vote share forecasts from a variety of sources including betting markets, polls, statistical forecasting models and citizen forecasts. As well as updating weekly, the methodology (as detailed below) might well evolve. So comments and suggestions on our approach and for new forecasts to include are welcome.

Just as they did last week, all the different sources point to the Conservatives being comfortably the largest party, with heavy losses for Labour and modest gains for the Liberal Democrats and Scottish National Party (SNP). Last week the betting markets suggested a smaller Tory tally than did the forecasting models. The models haven’t changed much but the betting markets have moved into line with forecasts. On average across betting markets, and complex and simple models, the Tories are expected to win with a comfortable majority of 60, barely changed from 57 last week. All three sources now suggest a majority of 50 or more.

Seats Betting Markets Complex models Simple models Average
Con 352 360 353 355
Lab 210 201 193 201
LD 37 25 30 31
Brexit 0 0 0
Green 2 1 1 1
SNP 46 48 50 48
PC 5 4 4 4
Con majority 54 70 56 60

Conservative Seats - 13th Nov

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2019 General Election, Combined forecast, Forecast updates, GE19 Combined Forecast

First combined forecast for the 2019 general election

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By Stephen Fisher, John Kenny and Rosalind Shorrocks (Universities of Oxford, Southampton and Manchester respectively)

There aren’t so many different forecasts for the general election out yet, but enough to start looking at how they compare. This is the first of hopefully weekly blogs where we review the different forecasts from different methods and combine them into an overall forecast. At the moment, the polls and seats forecasts suggest a comfortable Conservative majority but citizens and betting markets are not so sure it will happen.

The idea of combining forecasts from different sources has a good track record, though it has to be admitted that our attempts for the 2017 general election and the 2016 Brexit referendum did not work out well. We will write more about those experiences soon. Also worth noting is the experience of the pollyvote.com combined forecast of the US presidential elections.

Here we aggregate seats and vote share forecasts from a variety of sources including betting markets, polls, statistical forecasting models and citizen forecasts. As well as updating weekly, the methodology (as detailed below) might well evolve. So comments and suggestions on our approach and for new forecasts to include are welcome.

Continue reading First combined forecast for the 2019 general election →

Brexit, General elections, tactical voting

Leavers united could easily thwart divided Remainers

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This is a longer and more detailed version of a post that was originally published by Prospect here on Friday. The opinion polls published over the weekend do not collectively show any substantial change from the figures in the table below.

By Stephen Fisher, 9th September 2019.

The government has lost its majority in parliament, so it is unlikely to be long before there is a general election. Already at the last election, the Conservatives attracted most Leave voters while Labour was most popular among Remain voters. So what has changed in the party preferences of Leave and Remain voters, and with what implications for the next election?

The Conservatives lost many of their Leave voters to the Brexit Party at the European elections earlier this year largely because of the government’s failure to deliver Brexit on schedule at the end of March. At the same time, frustrated with the complexity and ambiguity in Labour’s position on Brexit, many Labour Remain voters switched to the Liberal Democrats or Greens.

Since May (the month and the leader) the challenger parties have waned and the two main parties have recovered somewhat, but Westminster-vote intentions are still closer to the multi-party competition we saw in the Euro elections than they are to the two-party dominance of the 2017 election.

The table shows how Leave and Remain voters from 2016 voted in 2017, and how they intend to vote now. The changes show that the rise of the Liberal Democrats and Greens has been largely confined to Remain voters, while the Brexit Party has, unsurprisingly, only really attracted those who voted Leave in the referendum.

Table: 2017 vote and current vote intention, by 2016 vote

  2017 2019 Change
  Leave Remain Leave Remain Leave Remain
Con 63 25 52 16 -11 -9
Lab 25 53 12 37 -13 -16
LD 3 12 4 32 +1 +20
UKIP/Brexit 4 0 27 1 +23 +1
Green 2 3 1 7 -1 +4
             

Note: 2017 figures come from the British Election Study Internet panel. 2019 figures are the average of the most recent poll from each of Deltapoll, Opinium, Survation and YouGov taken between 21 August and 3 September 2019. The UKIP/Brexit row shows figures for UKIP from 2017 and the Brexit Party in 2019, and the change between the two. 

What is perhaps more surprising is just how both main parties have suffered setbacks among both Leave and Remain voters. Labour have fallen back almost as much among Leave voters as they have among Remain voters. While the largest outflow from Labour in absolute numbers is that among Remain, in relative terms, it is the other way round. Labour have lost just under a third of their 2017 Remain voters, but as much as half of their former Leave voters. As a result, Labour supporters are even more predominately on the Remain side than they were in 2017. Continue reading Leavers united could easily thwart divided Remainers →