Can the 'yes' campaign win the Alternative Vote referendum?

Peter KellnerPresident
May 16, 2011, 4:53 AM GMT+0

The short answer is, yes they can – but not if they fail to grasp the size of the mountain they must climb.

Recently AV enthusiasts have seized on an ICM poll for the Electoral Reform Society which finds that supporters of AV outnumber supporters of First-Past-The-Post. These are the topline figures from an online survey ICM conducted from 26-28 November:

I would vote ‘Yes’ for the voting system to change to AV: 35%

I would vote ‘No’ – to keep the existing system: 22%

I would not vote in the referendum: 9%

Don’t know: 35%

YouGov’s figures are very different. We have been tracking this issue fortnightly for the past six months. Here are the two latest sets of results – from a poll with similar fieldwork dates to ICM, and our latest poll, conducted last weekend:

I would vote in favour of switching to the Alternative Vote: Nov 28-29, 35% (December 12-13 33%)

I would vote in favour of keeping first-past-the-post: 41% (39%)

I wouldn’t vote: 7% (7%)

Don’t know: 17% (21%)

So, while ICM finds a 13 point lead for the ‘Yes’ camp, YouGov’s two latest polls both show a 6 point lead for the ‘no’ camp. Which is right?

The first thing to say is that I have no quarrel with ICM’s sampling or weighting methods. ICM is an excellent company. Like YouGov, it has a good record at predicting elections with its eve-of-poll surveys. Sometimes ICM and YouGov results differ because ICM have generally conducted their polls by telephone, whereas YouGov’s polls are conducted online. There can be ‘mode effects’ – evidence from Britain and America suggests that some people will say one thing to telephone interviewers, and something else in an online survey where they do not have to worry about an interviewer’s response. Issues where ‘mode effects’ have been detected include taxation, sex, drugs, religion and, for some years, a willingness to vote Conservative. ‘Shy’ Tories used to be a problem for face-to-face and telephone polls, but not for online polls.

This time, however, we can rule out ‘mode effects’: both ICM and YouGov conducted their referendum polls online. Both also had samples of just over 2,000. This means we can also rule out sampling error as a reason for the gulf.

So: what ARE the differences that could explain why the two polls produce different outcomes?

The suggestion advanced within the ‘yes’ camp is that YouGov’s question reminds people that the referendum is being proposed by the Coalition, whereas ICM’s question does not. Here is what Mark Pack wrote last week for the Liberal Democrat Voice website (and the party’s finest election guru, Lord Rennard has made the same point:

‘There is an important difference between the wording of the two polling questions, with YouGov’s starting: ‘The Conservative-Liberal democrat Government are committed to holding a referendum…’, whilst ICM has no mention of the Conservatives in its question, which begins: ‘A referendum is due to be held…’ Though there are also other differences in the wording, this looks to be the most important difference.’

So, the case against YouGov is that, by mentioning the Conservatives and Liberal Democrats, some people are reacting, either favourably or unfavourably, to the Coalition itself, rather than to the issue of voting reform.

Fortunately, this is easy to test. On December 13 and 14, YouGov repeated its question, among a fresh sample, in which we changed the start of the first sentence to read: ‘A referendum will be held next May to decide whether Britain should change the system for electing Members of Parliament….’ In every other respect, our question was the same as our tracker question. Here is how the two recent YouGov surveys compared:

Dec 12-13 Coalition mentionedDec 13-14 Coalition NOT mentioned

I would vote in favour of switching to
the Alternative Vote



I would vote in favour of keeping



I wouldn't vote



I don't know



These are statistically identical results. It appears that it makes little or no difference whether we do or do not mention the coalition in the introduction. In fact, there probably IS a slight difference. Conservative supporters are slightly less hostile to AV, and Labour supporters slightly MORE hostile, when the coalition is mentioned. But the differences are modest and, overall, cancel each other out.

So – the explanation advanced by the ‘yes’ camp seems not to work. What, then, is the reason?

My belief is that the answer is to be found in what Mark Pack dismissed as the unimportant ‘other differences’. Here are the standard ICM and YouGov questions in full:


The Conservative-Liberal Democrat Government are committed to holding a referendum on changing the electoral system from first-past-the-post (FPTP) to the Alternative Vote (AV). At the moment, under first-past-the-post (FPTP), voters select ONE candidate, and the candidate with the most votes wins. It has been suggested that this system should be replaced by the Alternative Vote (AV). Voters would RANK a number of candidates from a list. If a candidates wins more than half of the ‘1st’ votes, a winner is declared. If not, the least popular candidates are eliminated from the contest, and their supporters’ subsequent preferences counted and shared accordingly between the remaining candidates. This process continues until an outright winner is declared.
If a referendum were held tomorrow on whether to stick with first-past-the-post or switch to the Alternative Vote for electing MPs, how would you vote?


A referendum is due to be held in May 2011 on adopting a new voting system for British parliamentary elections. The proposed new system is called the ‘Alternative Vote’ (AV). If the referendum on AV were held tomorrow, how would you vote?

The big and obvious difference is that the YouGov question explains the difference between AV and FPTP, while the ICM question does not.

I believe that this holds the clue to the main difference between the two sets of results. It should be noted that ICM and YouGov agree on the proportion of people who support AV. The two sets of results differ in support for FPTP (YouGov in late November 41%, ICM 22%) and the number of don’t knows (YouGov 17%, ICM 35%).

It looks as if many people say ‘don’t know’ when the rival systems are not explained, but prove averse to change when they ARE explained. Here are three reasons why this is plausible.

First, when YouGov conducted a survey for the Constitution Society three months ago, we found that only 33% said they understood AV. 35% said they had heard of it but were; ’not sure how it works’, while 32% said they hadn’t heard of it.

Second, the same survey indicated that, overall, the more people are exposed to the arguments for and against changing to AV, the more they prefer FPTP. (Full results can be seen at here).

Third, YouGov separately conducts tracking surveys for the academic British Election Study. Our referendum question is:

How will you vote in the May 2011 referendum on a proposed change in the UK electoral system? Do you want the United Kingdom to adopt the 'alternative vote' system instead of the current 'first past the post' system for electing Members of Parliament to the House of Commons?

The most recent results of the YouGov/BES survey, conducted between November 23 and December 7, were:

Yes, adopt the alternative vote system: 34%

No, keep the first past the post system: 34%

Don't know: 27%

Will not vote in the referendum: 5%

As can be seen, these figures lie between ICM and YouGov results – but, again, the pro-AV percentage is virtually identical; the differences concern the figures for ‘no’ and ‘don’t know’.

There is one further vital set of evidence to help us see what is going on. YouGov has been asking the same question fortnightly for the past six months. In each of the first five surveys, from mid June to early August, more people said ‘yes’ than ‘no’, though the lead generally declined. In each of the ten surveys since mid August, more people have said ‘no’ than ‘yes’, with the ‘yes’ vote stabilizing at 32-35% since early October, and the ‘no’ vote stabilizing at 39-43%.

The YouGov/BES series started in September, but this, too, has seen a modest move from ‘yes’ to ‘no’.

As for ICM, the question it asked for the Electoral Reform Society was new, so we cannot track movements in attitude. However, in the weeks after the election it did ask the same question twice, first for the Sunday Telegraph and then for the Guardian:

The new Government has said it will hold a referendum on whether to replace our current voting system, first past the post, with the Alternative Vote, which allows voters to express more than one preference. How will you vote in this referendum? Would you vote to...

May 12-13Aug 13-16

Introduce the new Alternative Vote system



Keep the current First Past The Post system



Don't know



The figures were different from YouGov, but the direction of change was the same – initial public support for AV during the coalition’s honeymoon period, followed by a drift towards keeping FPTP.

I draw these conclusions from this analysis.

  • For the time being, only a minority of people fully understand the difference between AV and FPTP
  • As a result we should not be surprised that polls differ depending on whether the difference is or is not explained
  • Either way, the ‘yes’ campaign has lost ground, and the ‘no’ campaign gained ground since early summer
  • As the referendum approaches and the impact of the rival campaigns is felt, more people will get to know the differences between AV and FPTP
  • The quality of the campaigns could make a big difference to the result
  • The full impact of the campaigns may not be felt until the final few days
  • By then – though not, perhaps, until those last few days – I would expect the gap between ICM and YouGov’s results to narrow significantly.
  • Meanwhile, at a time when so few people understand the rival systems, I believe it makes sense to describe them briefly. But there is no absolutely ‘right’ or ‘wrong’ approach: a case can be made for questions that provide no information and obtain a ‘top of the head’ response. The point is to recognize that YouGov and ICM are measuring different things, and to seek to understand those differences

At this stage, my best guess is that, if the two campaigns are evenly matched, there will be a ‘no’ majority next May. But there is much room for the campaigns to make a difference to the outcome. In particular, a vigorous ‘yes’ campaign among Labour voters could sway the result, because it is Labour supporters who have shifted most strongly since June from ‘yes’ to ‘no’.

Whatever happens, YouGov will continue to monitor and report on the public mood as the referendum approaches.