Historical polls

How low can Labour’s support go? What past elections & European politics suggest – Polling Matters

Posted in Historical polls, Politics, Polling Matters on October 27th, 2016 by Leo – Comments Off on How low can Labour’s support go? What past elections & European politics suggest – Polling Matters

On Polling Matters this week I talked about what might happen to Labour’s support over the rest of the Parliament.

Regular readers of this site might remember that I’ve previously compared how oppositions have stood in the polls 18 months after elections with how they then did at the subsequent election (using Mark Pack’s brilliant collection of historical polling data).

For this week’s episode I updated this analysis with the 2015 election (which was an outlier, as Labour underperformed how they’d be expected to do – largely because of the polling miss). The analysis suggests that, between this point in a parliament and the subsequent election, polling leads typically roughly halve.

This happens regardless of whether it’s the government or the opposition that’s leading in the polls at this point.

I found this surprising and it seemed like it can’t be right. I had thought that this was typically a low point for governments, and that they usually recover support by the time an election comes. But the evidence doesn’t really seem to bear that out – and it appears the opposition did gain ground ahead of the 2001 and 2005 elections.

Obviously this is a crude model. It doesn’t take into account many things. But for what it’s worth it suggests that Labour – currently about 12pts down – is on course for a 6pt election defeat, which is less than I’d expected.



But here’s another view on the question of Labour’s polling floor.

If we look at other centre-left European parties that, like Labour, were scoring between 35-45% in the late ’90s and early ’00s, we don’t see much evidence that Labour is currently at the lowest point it can get. All of those parties have scored lower than Labour in national parliamentary elections. Most of the others have gone below 25%.

Clearly different electoral systems – and national politics – are an enormous factor. What happens in one country isn’t inevitably replicated in another. But this alone suggests that Labour has no assurance it can call on the support of 30% of the public at a general election. Other major centre-left parties have found that the ground can indeed fall away beneath them.


I talked about this, along with Ukip and Theresa May’s in-tray, with Keiran and Asa Bennett of the Telegraph.





A year of Corbyn: how the Labour leader compares with his predecessors

Posted in Historical polls, Labour leadership, Politics on September 11th, 2016 by Leo – 1 Comment

The day Corbyn took over as Labour leader I posted a chart of how his predecessors had done in their first 12 months, so we could compare polling of Labour during Corbyn’s first year. Every three months I’ve checked in on progress (here, here and here).

Corbyn has been in charge of the party for a year and here is the last update in the series (methodological note below).

It shows that Labour is not the most unpopular it’s ever been at the end of a leader’s first year. Fewer people said they’d vote Labour in 2008 than say the same now. Labour has no less support now than it did after Michael Foot’s first year.

You could argue either way about how badly the precedent suggests Corbyn’s doing. On the one hand, every other Labour leader who took over in opposition when it was polling below 40% (Kinnock, Smith, Miliband), finished their first year with it above 40%. Corbyn finishes his first year at around 30%.

On the other hand, Callaghan, Foot and Brown all lost much more support in their first year than Corbyn did. So it’s hard to argue, using just this data, that he’s the most unsuccessful post-war leader.

The comparison also suggests that the leadership challenge (which came between the 9- and 12-month points in this chart) has had little effect on voting intention. Polling of Corbyn’s Labour has followed a common historical pattern: gaining support in its first six months, then losing it in the second six (as did Gaitskell, Wilson, Kinnock, Smith and Blair).

First 12 months

Given where Labour is now, how can it expect to do at the next election?

A rule that has never been broken is that Labour oppositions always lose support between the end of their leader’s first year, and the general election.

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Seven months to go, historical polls still point to a narrow Tory election lead, with Labour the largest party

Posted in Historical polls, Politics on October 1st, 2014 by Leo – 1 Comment

Seven months until the General Election it’s time for an update of my chart of what historical polls and votes can tell us about the election ahead.

The earlier posts are available here, including discussions of the methodology. As ever, I’m using Mark Pack’s brilliant spreadsheet of historical polls.

The new analysis suggests that:

Opposition lead at the election =

(0.6 x Opposition lead seven months before the election) – 4.3pts

According to UK Polling Report, Labour’s current lead is 4pts. This means the analysis suggests a Tory lead after the election of just under 2pts: probably not enough for a majority, and with Labour the largest party.

This is almost exactly the same prediction as from polls a year before elections. It is also similar to – though marginally better for the Tories than – the prediction from polls two years before elections.

But now focus on the elections in the area in the red box below: where the polls were narrow at this stage. In these cases there is a huge amount of variation in the results: from a healthy Opposition victory (’79) to a comfortable Government majority (’87).

So from where we are now, previous elections suggest either main party could build a majority-sized lead.

That said, the fact the polls have followed the historical trend for at least the last 17 months provides some evidence to support the model’s prediction of a very small Tory lead.

Health warnings

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12 months to go, historical polls suggest a knife-edge election result

Posted in Historical polls, Politics on April 9th, 2014 by Leo – 7 Comments

In two previous posts, I looked at how we can use past polls and elections to shed light on what current polls tell us about the next election. Today, I’m publishing an update, on how to interpret polls one year before the election: less than a month from now.

The interesting bit

According to the historical trend, election results relate to polls 12 months before as:

Opposition lead at the election =

(0.5 x Opposition lead a year before the election) – 3.5pts

That is, on average, polling leads halve (whichever party is leading) and move 3.5pts in favour of the government in the 12 months before an election (the real-world logic of requiring these two steps isn’t obvious and there’s no suggestion they actually happen in this order – but it’s what the regression produces).

This means, a Labour lead of 6-8pts 12 months out would point towards a tie in vote share at the election – making Labour the largest party and probably just short of a majority:

'79 and '87 had seriously odd 12 months before the elections

This would suggest Labour’s current poll lead – 4pts – points towards a narrow Tory win on vote share at the election, of around 1.5pts. Again, this would probably put Labour as the largest party.

Should you pay any attention to this graph?

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What do old polls show about the next election?

Posted in Historical polls, Politics on January 12th, 2013 by Leo – 1 Comment

I wrote a post last year about old opinion polls and how well they predict future elections. It compared election results with polls taken 18 months after the previous election, and also compared polls taken two years before an election to the result of that election.

It’s now coming up to two years before the next election and the second part of my post has got a bit of attention.

John Rentoul in the Independent on Sunday argued that this kind of analysis is all well and good but we shouldn’t pay too much attention to where the polls are at the moment – there are too many unpredictable events that will change things over the next two years, and what matters is how the parties respond to them.

On Labour Uncut, Rob Marchant focused on the implications of the “two years before the next election” chart (below) and concluded that Labour is on the border between being on course to win in 2015 or not.

The “two years out” data do suggest, as Marchant says, that Labour’s current 11pt lead is about on the cusp of where an opposition needs to be if it’s to have most votes at the election. Only once – ’64 – has an opposition won when it’s been ahead by less than 10pts at this time.

But Rentoul is right that current polls can only take us so far: indeed the regression showed a 40% correlation, not a perfect prediction.  Events, and the parties’ reactions to them – politics – will do most of the shaping of what happens, and whether Labour’s lead goes up or down.

This is probably about as far as we can get looking just at overall national voting intent and past elections. But we can learn more by digging a bit deeper into where Labour’s lead came from.

About 15% of Labour’s current support is from people who voted Lib Dem in 2010*. It was their move to Labour in late 2010 that gave Labour a polling lead which it has kept pretty much consistently (except a brief period in early 2012). The fact these voters have largely stayed with Labour for two years suggests their support is fairly stable. But who knows what they will do when the Lib Dems start stepping up an election campaign, or if Clegg is dropped and the Lib Dems start trying to present a clean slate.

And it’s important to think about how this Lib Dem defection will work at the constituency level. Several people have written about this, but for me this piece by Mark Gettleson nails it. There are 33 seats where the Tory majority over Labour is less than the proportion of the vote that moved from Labour to the Lib Dems between ’97 and ’10. If these move back (though in 18 years there’s a lot of churn in a constituency), Labour would gain those seats directly from the Tories. (There are of course also seats, balancing this, that the Tories will be trying to take off the Lib Dems – 20 of their 40 targets)

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Past elections suggest Labour’s prospects are better than most commentators think

Posted in Historical polls, Politics on January 9th, 2012 by Leo – 7 Comments

Commentary on the difficulties facing the Labour Party – leading in nearly every poll for over a year – sometimes puts me in mind of Bill Shankly, the Liverpool manager of the ‘60s and early ‘70s. Responding to a journalist’s question about a supposed crisis at the club, the great man said, “Ay, here we are with problems at the top of the league”.

Likewise, despite Labour’s consistent polling lead, the impression from the comment pieces, blogs and tweets is of a party struggling to find supporters. The logic is that, firstly, Labour’s lead is smaller than might be expected against a government undertaking such spending cuts, and, secondly, that the government is likely to recover and overhaul that lead between now and the next election.

The first of those points may be subjective, but the second can be tested against what’s happened in the past. Mark Pack has compiled the voting intent results from all opinion polls published since 1945, which allows us to do just that.

November 2011 marked 18 months since the last general election. At that point, Labour were on average 4.6pts ahead of the Tories, a score that has since slightly reduced due to Cameron’s veto bounce.

Comparing this score with opposition parties’ poll scores relative to governments’ 18 months after past general elections allows us to benchmark how Labour are currently doing. It also allows us to estimate Labour’s result in the next general election.

A regression analysis of historical polls 18 months after an election, relative to scores in the next general election can provide a model to analyse where we are now (see below for the detailed methodology). The analysis suggests that performance at this point is in fact a pretty good prediction of performance at the next election: it predicts nearly 60% of the result of the next election, with a very high level of confidence (p=0.002).

If a party is leading at this point, it tends to be leading at the election. However, the gap between the government and the main opposition partly typically halves over the remainder of the parliament.

Therefore, given the current position, the historical data suggest Labour should expect to win the next election by a small margin, of a little over two percent.

However, these polls weren’t conducted equally far before the forthcoming election. The Feb ’74 election, for example, was 44 months after the previous election, while the 2010 election was 60 months after the previous one.

So, as well as comparing election results with polls 18 months after the previous election, we can compare the results with polls exactly two years before that election date.

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