Boris vs Ken: 10 days to the London election

Posted in London, Politics on April 23rd, 2012 by Leo – Comments Off

Today’s London poll has suggested that the mayoral race is still open, with Boris’ lead reduced to 2pts. It’s the first time since February that the contest has been so tight:

Since each of the last six polls, including today’s, has been within margin of error of a Boris lead of 5pts, it’s possible that the narrow lead just reflects random variance.

But digging beneath the numbers suggests a more decisive trend.

Between January and mid-April, Boris began scoring much better among 2010 Tory voters than Ken did among 2010 Labour voters. The gap became as wide as 14pts.

An explanation for growing support among previous Tory voters could be Lynton Crosby’s style of ‘get out the base’ campaigning.

But in the last two weeks, while Boris has neared the limits of support from 2010 Tory voters, the Ken campaign has made up more ground among Labour voters. The gap has now reduced to 7pts:

This may in part be a product of Labour’s current support in London now being at its highest point this year, 50%.

But even if Labour don’t increase their national support in the capital any further, there is still more space for Ken to increase his share among previous party supporters than there is for Boris to do the same.

The other voters

Last month we saw that Boris had just made a significant gain among people who wouldn’t vote Labour or Tory in a general election.

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Does the Evening Standard understand its own Boris vs Ken poll?

Posted in Bad polling, London, Media on April 10th, 2012 by Leo – Comments Off

I try not to write much about polling methodology. I doubt it’s of interest to many people, and besides, Anthony Wells does it much better than I do.

But there’s been some truly awful reporting today of the latest London mayoral poll, and it’s time to look at weighting and so on.

According to today’s Evening Standard, their new ComRes poll shows “a dramatic slide in Mr Livingstone’s support after his argument with his Tory rival over tax in a radio station lift”.

They go on to say that those “interviewed before “liftgate” last Tuesday morning were split 50/50 between the two candidates. But those surveyed afterwards divided 60/40 in favour of Mr Johnson.” ITV also reported it with the same angle.

This all sounds very plausible and interesting, but it’s in fact a bad misrepresentation of the poll.

The issue is, the poll was never designed to show how opinion changed after shoutyBorisgate. Of course it wasn’t: the poll was set up without anyone knowing there would be any event to compare ‘before’ and ‘after’.

If you do know that an event is coming, say a leaders’ debate, you can run two separate polls, with comparable samples (or even, with the same people), and see how the results compare.

But this ComRes poll doesn’t do that. Instead, a little over three quarters of the poll was conducted before the interview, and the remainder after. Nothing looks to have been done to make sure the samples before and after were comparable.

So we’ve got two groups of people. In terms of how they voted in the last general election (nothing to do with Ken and Boris), the first group has 29% Labour voters and 27% Tory voters. The second group has 26% Labour voters and 32% Tory voters. A Labour 2pt lead vs a Tory 5pt lead.

We then ask them how they’d vote in the London election, and are supposed to be surprised when the group with more Tories say they’re more likely to vote for the Tory candidate!

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The must-win voters in the London mayoral race

Posted in London, Politics on March 25th, 2012 by Leo – 2 Comments

The latest London mayoral poll puts Boris on 54%: the largest lead for any candidate this year, suggesting a 3pt swing from Ken.

The change may just be random fluctuation: with London polls still only coming about once a month it’s hard to be sure. But it would also make sense that we’re seeing an impact from the accusations about Ken’s tax dealings, which broke before the poll was conducted.

Regardless of what’s caused any swing, the combined polls this year demonstrate two key issues that are determining how the race is working out.

Converting party supporters

Given that Labour’s vote is generally much stronger than the Tories’ in London – yet Boris and Ken are roughly level – it’s not surprising that Boris is doing better among his party’s supporters.

So, one problem for the Ken campaign is that it isn’t getting support from all Labour voters. In the latest poll, Ken is 10pts behind Boris among their own parties’ supporters. While this isn’t new, the gap seems to have widened this month:

Labour’s vote across the country has increased by several points since the March poll was taken. Given the closeness of the London race, this could make a crucial difference, but the lower conversion rate of Labour voters into Ken voters could reduce the benefit to the campaign if the same reluctance applies to ‘new’ Labour voters.

Winning other voters

There’s a striking difference in where each candidate’s support comes from. Despite Ken’s relative weakness among Labour voters, a much higher proportion of his voters are also Labour supporters than Boris’ voters are Tory supporters.

In fact, less than two thirds of Boris’ support comes from Tory voters, while five in six Ken voters are also Labour supporters.

The issue is that Boris is winning support outside his party base far more successfully than Ken is, and the latest poll puts this support at its highest point so far:

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Boris vs Ken: London polling 10 weeks from the election

Posted in London, Politics on February 22nd, 2012 by Leo – 1 Comment

Since we’ve now had three polls on the London mayoral election since mid-January, now seems a good time to look at what they tell us about the race.

When the last poll came out, Ken’s lead seemed a real surprise. In retrospect, perhaps it shouldn’t have done. Despite the shocked reaction, previous polls had suggested the race would be close: Ken’s January lead didn’t represent a sharp reversal in opinion, but actually a restatement of what we’d seen before.

So in this context it’s not hugely surprising that the two more recent polls have also found the race to be on a knife edge. Two of the three put Ken narrowly ahead, and the third gives it to Boris – but all are within the margin of error:

In terms of where these numbers might go, I would echo my previous suggestion that Boris could be boosted by an incumbency effect, but Ken might expect Labour’s overall showing to increase a couple of points in the next few months if, as seems likely, the Tories gradually lose the boosts they had from the EU walk-out and Miliband’s bad January (bad in terms of immediate poll reactions).

There also continues to be a ‘Labour for Boris’ vote as well as a ‘Tories for Ken’ crowd, as pointed out by Mark Gettleson at Politics Home.

But the ComRes poll in particular demonstrates an interesting point about where the polls might go from here.

A set of questions about each candidate suggest stark differences in their strengths and weaknesses. While Ken is seen as understanding ordinary Londoners’ concerns, it is Boris who is seen as the man with the plan, and the ability to deliver on his promises. This is reflected not just among the whole sample, but also in the opinions of each candidates’ own supporters:

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Boris vs Ken just got a lot more interesting

Posted in London, Politics on January 19th, 2012 by Leo – 3 Comments

YouGov today have a poll that has radically changed expectations for this May’s London mayoral election.  Previous polls had suggested that Boris Johnson was on course for a comfortable re-election, but today’s poll has put Ken Livingstone narrowly ahead, give or take a margin of error.

Since polls on the vote have been relatively sparse, we can’t easily tell whether this is an outlier. But when looking at where Ken has got his boost, the results make intuitive sense.

Quite simply, Labour voters have shifted strongly into the Ken camp, as the charts below show.

The first shows how Tory supporters would vote in the London election, comparing last June with today’s poll.  There has been very little change, with Boris taking pretty much all their votes.

But when we do the same for Labour supporters, we see a large movement of Boris voters into Ken’s pile:

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