All posts by electionsetc

How did the election forecasts do in 2017?

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?

Second combined forecast for the 2019 general election

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

Continue reading Second combined forecast for the 2019 general election

First combined forecast for the 2019 general election

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

Leavers united could easily thwart divided Remainers

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

Two Notes on the Psephology of the Euro-Elections

by John Curtice, Patrick English, Stephen Fisher and Eilidh Macfarlane.

Even though the votes have yet to be counted, the Conservatives and Labour already seem to be undertaking their own post-mortems of what promises to be poor results for both of them in the European Parliamentary elections. Within the Conservative party there is a lively debate taking place about whether or not in the wake of the anticipated success of the Brexit Party, Tories could and should embrace at least the possibility of leaving the EU without a deal. Meanwhile, Labour, anticipating perhaps that the party has lost votes to others whom have adopted a clearer position on Brexit, looks as though it is about to consider the possibility of coming out more firmly in favour of some kind of public ballot.

Doubtless, all sides in this debate will look to the pattern of the results on Sunday for evidence to support their view of what their party should do. There has already been some speculation that the pattern of reported turnout in this election (information about which has already been released by some councils) suggests that voters in more Remain-inclined areas were more likely to turn out to vote, indicating perhaps a new determination among anti-Brexit voters to express their views at the ballot box. Meanwhile, we can anticipate that the results themselves will be poured over for evidence that the Conservatives or Labour have lost ground more in Remain-voting areas than Leave-inclined ones or vice-versa. However, in both instances caution will be required in interpreting the evidence when the full panoply of results is unveiled on Sunday night.

Turnout

First of all, we consider the evidence on turnout. Two patterns can be observed in the data available so far. (Our evidence comes from the figures for 143 councils where the data have been collected by Matt Singh and/or Patrick Heneghan.) The first is that turnout appears to be up by a couple of points or so on 2014, and thus may well be a little above the average for previous Euro-elections. The second is that turnout appears to have increased more in those areas where a majority of voters backed Remain in 2016 than it has in those places where Leave were most popular.

Two notes of caution about the data on turnout are in order. The first is that the figures on turnout released so far are based on the total votes cast, including votes that might eventually be deemed invalid; turnout is conventionally calculated in the UK on the basis of the total number of valid votes cast, that is, excluding those votes which are deemed to be invalid. These amounted to 0.5% of all votes cast in 2014, enough to reduce the turnout as conventionally calculated by 0.2%. So even if the figures released to date prove to be representative, any increase in turnout is likely to prove a little less than has been reported so far.

Continue reading Two Notes on the Psephology of the Euro-Elections

Calculating the Local Elections Projected National Share (PNS) and Projected House of Commons in 2019

By John Curtice and Stephen Fisher.

A key summary statistic of the outcome of each year’s annual round of local elections is the so-called Projected National Share (PNS). This is an estimate of the share of the vote that the principal parties would have won in a GB-wide general election if voters across the country as a whole had behaved in the same way as those who actually voted in the local elections. It provides a single, seemingly straightforward measure of party performance that can tell us not only how well or badly a party has done as compared with four years ago (when, typically, most of the seats up for grabs were last contested), but also as compared with any previous local election for which a PNS is available – even though the places in which local elections are held varies considerably from one year to the next.

In this blog we provide some guidance as to how the PNS is being calculated this year by the BBC and how it will be used to project an outcome in terms of House of Commons seats.

Continue reading Calculating the Local Elections Projected National Share (PNS) and Projected House of Commons in 2019

Forecasting Local Election Net Seat Gains/Losses 2019

By Stephen Fisher.

Updated 23:00 on 1st May to include a poll-based forecast I did not previously have access to, and to clarify figures for the Rallings and Thrasher local by-election model based forecast.

My predictions for this week’s bumper crop of English council elections are given in Table 1 below, along with those of others. The changes are relative to (sometimes notional) results for 2015 when the seats were last fought.

Table 1. Forecasts for English local election net seat changes 2019

Forecast Range R&T (local by-election model) R&T (local vote intention poll) Hayward
Con -700 -90 to -1,300 -405 -1,100 -800
Lab +590 +200 to +990 +150 +840 +300
LD +350 -10 to +720 +400 +170 +500

R&T refers to Colin Rallings and Michael Thrasher. Their figures are, I’m told, in the hard copy version of their Sunday Times article. (They differ slightly from those on Sophy Ridge on Sunday and others being attributed to them on Twitter.) Their local by-election model takes the results of recent local by-elections to predict the National Equivalent Vote (NEV) and projects the implied NEV changes since 2015 at the ward level (perhaps using notional results where required.) The local-election vote-intention poll Rallings and Thrasher used was conducted by Opinium which had the following shares of the vote: Con 28, Lab 36, LD 10, UKIP 9. That poll-based forecast is also mentioned in this excellent blog on the background to the local elections, which includes great data visualisation.

Continue reading Forecasting Local Election Net Seat Gains/Losses 2019