The Guardian’s report on their poll this month has made the assumption that a drop in Conservative support is due to NHS policy, various other commentators have this morning jumped to the same conclusion.

The truth is, as ever, rather more complex than that. Firstly we should set aside the ICM poll apparently showing a 4 point drop in Tory support as the NHS row continues. This is a classic case of making the outlier the story, the media’s constant failing in reporting polls – the underlying trend in polling is ignored while the rogue poll (and the reversion to the mean afterwards) gets a headline. Looking at the broad range of polls the Conservatives have not lost four points of support: they have gone from a position in December when, after the European veto, they appeared to be slightly ahead of Labour in the polls to a position this month when they appear to be a point behind or so, a drop of one or two points.

Many commentators today have also fallen victim to a fallacy I often see in the comments here – ascribing whatever movement happens in the poll to whatever subject they personally feel strongly about. Hence the Guardian and many bloggers feel strongly about the NHS, there has been a slight drift downwards in Tory support, therefore the former is probably the cause of the latter (it’s also a sort of availability bias – the poll contained questions about the NHS, they are bad, therefore that’s the cause. What if the other questions in the poll had been about, say, crime?)

However, this ignores other possible explanations, which could actually be better evidenced. Here are a couple, though I certainly wouldn’t claim these are exhaustive – there are no doubt other possibilities, including those that are less well served with tracker polls.

The first hypothesis is the unwinding of the European veto effect. You will remember that in November Labour had a lead of four or five points. The Conservatives then pulled level after David Cameron’s veto at the European summit. We should be expecting the effect of the veto to gradually unwind and, indeed, there is evidence to suggest that is what we are seeing.

The proportion of people thinking that Europe was an important issue facing the country peaked at 38% just after the veto, but has since faded away again, and is now back down to 23%. Similarly we saw some sharp increases in perceptions of David Cameron on the back of his veto. The percentage of people thinking Cameron “sticks to what he believes in” rose from 26% to 39%, decisive went from 20% to 29%, good in a crisis went from 13% to 18%. Since then most of these figures have fallen back down a bit (“stick to what he believes in” back to 31%, decisive back to 24%, good in crisis back to 18%).

One straightforward explanation therefore is just the fading of the leadership boost that Cameron received from the veto.

A second hypothesis is less negative coverage of Ed Miliband. In January the media narrative was dominated by criticism of Ed Miliband’s leadership, and the media impression was increasingly that he was a no hoper. In February that has faded a bit, the attacks have mostly stopped coming, he’s had a few good PMQs under his belt and the media narrative has largely moved on (to a great degree to the NHS!). This is reflected in Miliband’s own ratings. In January he hit record lows in his approval ratings, reaching a nadir of minus 53 points. In February he has recovered a but to the low minus 40s. His ratings are still significantly worse than they were last year… but he has risen off the canvas.

A third hypothesis is the NHS. The recent coverage has certainly pushed the NHS up the agenda – going back to the YouGov issues tracker, the proportion of people naming the NHS as an important issue is up to 32% from 22% a month ago. We also have lots of questions that have shown the government’s policy is unpopular and that people don’t trust the Conservatives on the NHS, but these don’t necessarily indicate change – it could’ve been unpopular all along.

The ICM poll yesterday shows that people trust the Conservatives less on the NHS now than in 2006, which is an interesting finding in itself, but it doesn’t follow that the drop in trust has come in the last few weeks or is a result of the current policy. If we look at YouGov’s regular tracker on which party people trust the most on the NHS there is a distinct lack of any recent drop in the proportion of people who prefer the Conservatives on the NHS.

In fact, the Conservative trend in the last year is pretty flat – what drop there was happened in late 2010 as the government’s honeymoon faded. What is also worth noting in this graph is that the Conservative detoxification on the NHS is something of a myth – it never really worked very well, and Conservative leads on the NHS were small and transitory.

This, I suspect, is one of the reasons the NHS hasn’t damaged the Conservatives that much – most people never trusted them on it in the first place. The other reason is that most people have no clue about the reforms and what they are or are not likely to do – take this recent YouGov poll for the Sunday Times which, rather than tell people about the reforms and ask about them, just asked people to say if they supported or opposed them based on what they’d seen or heard about them. 48% of people were opposed… but over a third (34%) of people said don’t know, a comparatively high figure for any question.

That is not to say that the NHS reforms are not politically dangerous for the government – I think Tim Montgomerie’s point that any future problems with the NHS (and there will always be some problems with the NHS, even if there were not budget squeezes and reorganisation) will be blamed on the policy is well made. Equally, just because it hasn’t made a big impact so far doesn’t mean it couldn’t do so in the future.

However the claim that it is already doing significant damage the Conservatives in the polls is weak. The drop in Conservative support in the polls is small and there are alternative and perhaps better evidenced explanations for it.

307 Responses to “What causes poll movements”

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  1. @anthony wells
    The usual very readable and informative job. I fell for it and needed Boo Boo to remind me that the 5 point lead last month, was never really theirs to lose.
    As for the Tories having their reputation on the NHS damaged, quite so, what reputation? Not a thing that was ever very beneficial to them. It is an offshoot of the general mistrust and doubt about Tory good intentions on the NHS, that cause a public sodden in ignorance regarding Lansley’s proposals, to largely give credence to Labour’s criticisms without much thought.
    The economy in reverse.

  2. @Anthony

    “The truth is, as ever, rather more complex than that. Firstly we should set aside the ICM poll apparently showing a 4 point drop in Tory support as the NHS row continues. This is a classic case of making the outlier the story, the media’s constant failing in reporting polls”

    I presume you mean that last month’s ICM showing the Tories 5% ahead was the outlier, not this month’s showing a Labour lead, or are you suggesting vice versa? And where’s the man who on these very pages four or five week’s ago, on seeing the 5% Tory lead, swore blind that this was the poll to believe, not all the others, because ICM were the “Gold Standard” of pollsters?? It’s all very confusing, isn’t it.

    Of course, there is always the danger that we dig around in the entrails of polls, looking at the ins and outs of their statistical methodology and forget their true purpose in life; the accurate measurement and representation of opinion. I have to say, I’m not interested in a poll whose figures may all add up neatly and symmetrically but gives me duff information, I just want to see a poll that, within the normal margin of error, is accurately telling me what the great British public is thinking at any given time.

    No too much to ask, is it?

  3. Another consideration is wheher an event (such as the veto) can make much difference when it is superceded by other events whether these are in the same drection or not.

    A running controversy like the NHS may be better remembered, but it may take longer to get up steam and lessreadily noticed.

    It is pretty obvious now that the last months ICM was an outlier. The vast majority of polls have put the Tories neck and neck, with a the majority of one point leads going to Labour. This 5 pointer was clearly wrong. If you remember there have been one if not two 4 point Labour leads recently, they vanished like Scots mist, (no need for comment Old Nat). It becomes clear that the best polling, ICM, or You Gov can slip from time to time. To be concerned that you are not getting the full picture, is, I think going a bit over board, its boring and its neck and neck.

  5. Crossbat – this ICM looks very much par for the course, it was the last one that looked odd (although one can never really say for sure… and certainly one can rarely say a poll is a “rogue” rather than just being towards the edges of normal margins of error. That is, incidentally, why I tend to say outlier rather than rogue, as the latter has a specific definition).

    Going back to the post though – a rogue poll produces two opportunities for duff stories, the poll itself… and then when the next poll shows a reversion to the mean that gets written up as a some important shift as well.

  6. Ignoring how the media jumps on one poll for a moment.

    Europe down the agenda from 38% to 23%, NHS (a traditional area of Conservative weakness – surely Cameron’s special pleading did lessen this to some extent before the GE) up from 22% to 32%.

    We have not had an NHS “event” to compare with the veto, but we can’t really discount the NHS… we are not in a political vacuum with a fading veto and lessened attacks on Miliband… as they fall in prominence other things reappear – in this case the long running Lansley bill saga rumbles on.

    Rawnsley last week speculated (with a “government source” quote) that Cameron fears looking weak if he u-turns on the bill at this late stage. Given the electioneering about “no top-down reorganisation” (perhaps a little too clever) “sticking to what he belives in” will cut both ways, and the opportunity to “decisively” dispatch Lansley seems to have passed.

  7. @billy bob
    It has obviously not occurred to you that DC may not want to get rid of Lansley . The left have a map of the world which considers any Tory involvement with the NHS must be intrinsically bad. Perhaps Cameron really believes that these changes are totally necessary.

    ps It is rather like me continually stating Ed Milibands comments about bankers remuneration is hot air and he wishes that he could leave the subject of bankers bonus’s alone. In reality I am sure, right or wrong, he means what he says.

  8. Forgive me but can i claim an assist, from the last thread?

    February 21st, 2012 at 9:14 amJim Jam

    Re ICM and Today.
    Regardless of the reach and the fact that Today are portraying as a 3% swing, NHS etc which favours my party I find it annoying.
    We all know that there has probably been a 1% or so swing Con-Lab since the last ICM poll but moe, sample variation etc is suggesting more.
    Just as the 1% Coms Res poll was raised by right wing media commentators the use of one poll in islolation is frustrating.
    As Anthony has said ‘poll shows no little or change’ isn’t a very eye-catching headline so only ‘interesting polls get extra coverage even if they are unreliable on their own.
    At least at GE time one rogue or extreme moe poll will normally be drowned out by plennty of others and averaged out by the ‘poll of polls’ (which have their won issues of course”

  9. Does anyone think that if DC was told after the GE that we would be seeing the type of polls in Feb 2012 that we currently are seeing that he would have been happy with that?

  10. @Roly1
    “Perhaps Cameron really believes that these changes are totally necessary.”

    Indeed. And also, I suspect that the reason we haven’t seen much evidence of tensions within the coalition is that Clegg and the other Orange Bookers share Cameron/Lansley’s view, irrespective of opinion within the wider membership of Clegg’s party.

  11. @roly1 – “DC may not want to get rid of Lansley.”

    DC is definitely averse to making any changes in the cabinet unless he really has to. A number of commentators belive that he will let go of of the poorly performing Lansley though – but not until after the bill (in whatever form that takes) has been finally passed. The fact that Lansley used to be Cameron’s boss will make that an awkward conversation.

    Not sure about the number two Simon Burns, but after hearing his impeccable Vincent Price sound-alike tones the other day – Hammer Horror is undergoing something of a resurgence atm. ;)

  12. Burns deserves a sideways move short of the cabinet for being the ‘face’ this last few weeks to protect Lansley.
    He has done a decent job presentation wise to be fair imo.

  13. ICM detailed tables are up here.

    Here’s the full breakdown of voting share from the initial raw data to the final published figure. Using the mean certainty to vote for each party in Table 1, I’ve been able to break down the turnout adjustment between the adjustment reflecting respondent’s own declared certainty to vote, and the assumption ICM make to downweight further by 0.5 those respondents who didn’t vote in 2010.

    A. Share of responses before adjustments other than initial weighting:
    C 34.0%, L 40.8%, LD 11.3%, Other 13.9%

    B. Final published poll as per the Guardian:
    C 36%, L 37%, LD 14%, Other 13%

    Causes of change from A to B:
    1. Turnout based on declared likelihood to vote
    C +1.0%, L -0.8%, LD +0.1%, Other -0.3%
    2. Additional turnout: 0.5 weighting to 2010 non-voters
    C +0.9%, L -1.4%, LD 0.0%, Other +0.5%
    3. Reallocation of DK/Refusals to 2010 party and rounding
    C +0.1%, L -1.6%, LD +2.6%, Other -1.1%

    In summary, a 6.8% Lab lead based on weighted responses is reduced to 1% in the published ICM poll. Of this reduction, 1.8% of the narrowing is due to what respondents say is their likelihood to vote, and 4% is down to what ICM themselves infer based on what respondents did in 2010, irrespective of what they say they’ll do now.

    Now there may well be a need to make some further adjustments additional to turnout weighting. But the question is, are ICM’s assumptions which underpin those adjustments robust ones, given that they make such a significant difference?

  14. imo the assumption that 50% (I think) of WV/DKs being assigned to the party they voted for last time is a reasonable one; the hold your nose notion.
    Many Lab supporters, including me, clung to ICM between 08 and 10 as they usually showed lab doing better as this adjustments worked in our favour at that time.

    Can a statto tell me how many % this is worth to the LDs and off the others as I assume higher ‘notional’ turnout reduces the adjusted figure those without DK/WV reallocation.

  15. Phil

    I like these analyses of yours. I suspect it takes quite a lot of work, and I’m grateful for that.

  16. Phil – posts crossed thanks nice work.

  17. roly1 @billy bob

    “Perhaps Cameron really believes that these changes are totally necessary.”

    Surely not. Heir to Blair.

  18. Great article Anthony-partic. the point about Cons NHS ratings.


    @”Perhaps Cameron really believes that these changes are totally necessary.”


    He , NC & AL ( unlike the opposition) are staring at the NHS cost forecasts & demand projections-and wondering how the hell they find the money to feed this black hole without writing blank cheques for future taxpayers to sign.

    Just like the problem of sustainability of Public Sector Pensions funding, NHS reform is a nettle to be grasped.

    DC grasped them both.

  19. Looking at Anthonys chart re preferred party on the NHS, I question, to what extent the response is based on true belief re the NHS rather than on which party you support overall. This comes across most significantly in the Lib Dem plot. The sudden surge in LD trust re the NHS occurs at the same time as “Cleggmania”. I can’t believe that Cleggmania was purely due to the LD stance on the NHS. In fact, I don’t recollect any big pronouncements from the Lib Dems on the NHS prior to the election.

  20. Crossbath

    Regardless of “how good” a pollster is, they CANNOT eliminate sample error (even by increasing poll sizes, which would reduce the margins of error slightly). 5% of polls will lie outside the 95% confidence interval. It’s the real weakness of monthly polling as we are left with the question “which poll is right?” (or is the truth in between?) with no way of knowing if the next poll is going to be comparable with the previous months polls or if “events” have moved the situation on.

  21. @OldNat, @Jim Jam

  22. @John B Dick – “Heir to Blair.”

    Blair (1997): “24 hours to save the NHS.”

    Mr Dorrell defended a Norwich Union campaign to stop people feeling “guilty” if they abandon the NHS.

    He said: “It seems to be an extraordinary definition of a free society that says you can buy Mars bars and foreign holidays with your money but you can’t buy health insurance.”

    Norwich Union is selling cut-price packages to jump waiting lists through deals with hard-up NHS trusts.

    But Mr Blair said: “Everyone will be treated according to their clinical need.”

    From memory NHS hospitals at that time were limited to 30% “pay beds”… Milburn reduced that proportion to around 2% in the majority of hospitals – in order to reduce wairting lists.

  23. @ Jim Jam
    ‘imo the assumption that 50% (I think) of WV/DKs being assigned to the party they voted for last time is a reasonable one; the hold your nose notion.’
    I tend to the view that ICM are mistaken in applying the spiral of silence to the LibDems in the same way that has happened re Tories and Labour voters – simply because far fewer people see themselves as core LibDem supporters.Much of their support is very soft with a significant inflow and outflow.The fact that somebody voted LD in 2010 does not make them a likely core voter who will return in due course – it’s simply where that person happened to be politically at the time in response to the Clegg factor etc.
    Fot that reason, I suspect ICM are overdoing the correction for a LibDem spiral of silence and pitching them a few points too high.

  24. A very good post

    Given that the last ICM poll was headlined as `Cameron soars in poll` in the paper,I think they are justified in giving a headline grabbing reason to the drop in conservative support…After all they are are in the business of selling papers and NHS reforms are in the news.

    I feel the NHS reforms may not damage the Tories as much as the Lib Dems…It may appear that Clegg is selling out to theTories,first on tuition fees and now on the NHS

  25. YouGov Con 37 Lab 41 LD 9 tonight, according to Sun/twitter.

    It’s not a Con lead – how come the Sun have released it early?

  26. Ian Anthony James

    “I feel the NHS reforms may not damage the Tories as much as the Lib Dems…It may appear that Clegg is selling out to theTories,first on tuition fees and now on the NHS”

    Relatively speaking, quite possible. Scottish LibDems are in a variant of the West Lothan Question

    Up till now the WLQ has been about Scottish Labour MP’s voting on legislation for England on matters devolved to the Scottish Parliament and which therefore does not affect their constituents. English nationalists in parties of the right are concerned about this anomaly. Since Scottish Labour, whether in the Scottish Parliament or at Westminster, is a UK organisation led from London, one may assume that the polices their MP’s promote in London would be supported by them if they were in Edinburgh or in their constituencies.

    Next week, Scottish LibDem MP’s, will be expected to vote with the rest of the coalition for a bill which many believe will fragment and privatise the NHS in England.

    They could not possiblydefend this if it applied to their own constituents. At least Scottish Labour MP’s were able to claim that they were in favour of the legislation they voted for. LibDems cannot win. Either they are hypocrites or quasi-tories.

    If they vote for this legislation the party in Scotland is finished at UK level. With tuition fees there was some wriggle room.

  27. “phil

    YouGov Con 37 Lab 41 LD 9 tonight, according to Sun/twitter.

    It’s not a Con lead – how come the Sun have released it early?”

    Perhaps the Sun will soon announce that they are dropping their support for the Tories and will back Labour. Now that would be nightmare for Ed M and Labour, as they will then have to ask Rupert whether he would kindly stop his news title from supporting them.

    How times change !!

  28. Nick Clegg wrote in the Daily Mail at some point before the GE, that he personally favoured a European style health insurance scheme… but no mention was made of that in the run-up to May 2010.

    It seems very likely that Clegg would support Lansley’s Health and Social Care bill… but I wonder how many LDs know that :)

  29. LDs foot soldiers have tabled a motion for Spring conference to “drop (section three of) the bill”.

    By all accounts the Downing St “summit” with friendly NHS representatives was polite but not so friendly after all. They refused to discuss the agenda which was about implementation – and instead expressed grave concerns about the bill. It seems even they are reconsidering their constructive engagement stance due to growing opposition from their memberships.

    Sun now tweeting a plunge in Tory VI.

  30. John B Dick

    I don’t know if you saw the Nottingham University report on NHS Scotland?,-says-study.aspx

    “According to the findings of a two-year report, post-devolution healthcare in Scotland represents a “groundbreaking” approach to the art of industrial relations.

    It has taken “arguably the most ambitious labour-management partnership so far attempted in the UK public sector” and made it work, say experts south of the border.”

    There have only been minor differences on NHS policy between SLab, SLD and SNP – and all have been committed to effective partnership between policy makers, management and staff in NHS Scotland.

  31. Oldnat

    Then that is in accordance with one of the founding principles which I have been waiting to see setting the style for all the agencies responsible to the Scottish Parliament.

    I have found verbose policy documents which point in anoher direction, but probably nobody reads that sort of stuff.

  32. Graham – good point perhaps 50% is too high.


    I can’t see the figures quoted on here in this link. Could someone direct me?

  34. “Scotland faces its first real-terms budget reduction since devolution, according to (Dr Brian Keighley ) the chairman of BMA Scotland, who claims it will have a ‘persistent damaging effect’ on patient care and morale.

    He said: ‘Despite the budget announcement made by the cabinet secretary, there is no denying that the NHS faces an unprecedented real-terms reduction in its budgets for the first time since devolution. It would be naïve to expect that this will not have an impact on patient care and access to healthcare services.”
    Feb 2012

  35. BooBoo,

    You need @sun_politics for their twitter feed………

    Billy Bob,


    You’re not normally a man for hyperbole :-)

  36. COLIN

    Presumably you approve, since the cut in the Block Grant was determined by the Coalition for reasons that they thought good.


    I find some of the table info difficult to understand. Looks like the polled a load of Labour men aged 40-59 and Tory women over 60.

  38. @Hooded Man

    First Tim Montgomery , now Mark Feild MP saying the NHS is becoming toxic – and the Sun tweeting non-Con leads.

    Plunge/dive/drop/dip, take your pick. ;)

  39. OLDNAT

    I neither “approve” nor disapprove.

    I just found it interesting that BMA disgruntlement is to be found in Scotland as well as England


    I didn’t realise that Westminster dictated the funding of NHS Scotland. I had imagined that it was a matter for the devolved administration to decide upon it’s public finances priorities within total funds available.

  40. @Billy Bob

    “First Tim Montgomery , now Mark Feild MP saying the NHS is becoming toxic – and the Sun tweeting non-Con leads.”

    What’s interesting about the Tory critics of the NHS Reforms is that, with the honourable exception of maverick MPs like Dr Sarah Wollaston, they don’t have any great objections in principle to the changes being proposed; their disquiet is born primarily of political expediency. They’ve seen which way the wind looks to be blowing and sensed serious political trouble ahead for their party. Some MPs with small majorities might even be fearing for their seats and I wouldn’t assign too much in the way of noble motives to their internal dissent. It’s much more likely to be that their main concern is their political skins.

    As a rule of thumb, I’d always be sceptical of politicians who bemoan a lack of presentational skills as the reason for a policy falling apart.

  41. “If you remember there have been one if not two 4 point Labour leads recently, they vanished like Scots mist, (no need for comment Old Nat). ”

    You were saying? Lol.

    I’m not sure the veto and Miliband-bashing effects have entirely unwound, although there definitely has been an unwind- the Conservative vote is still somewhat higher and the Labour vote ever so slightly depressed from their respective positions at the beginning of November.

  42. Colin

    I fear you misunderstood (or perhaps didn’t read) the research. Policy makers, management and staff are in agreement that more limited funding will affect services.

    However, they work together to minimise the problem. Is everything perfect? Of course, not. Will there be a bit of posturing all round? Yep.

    What we don’t have is a significant gulf between the different “stakeholders” (dreadful word!) as to how the service should be organised.

  43. Hannah

    I know there’s no need – but I can’t resist! :-)

    I’m impressed by your cultural sensitivity, but the term is actually Scotch mist, like Scotch whisky, and Scotch beef.

  44. @ Old Nat (9.24)

    Interesting article. Further confirmation, if any was necessary, that regardless whether Lansley’s bill is good for the NHS or not (and most of us think not) it will never work because it has not got the support of those involved.

    Surely it is commonsense that for any venture to be successful it has to have the support of those involved. This applies in business and in all types of venture. I find it very difficult to understand how the government can fail to see this. As it is now obvious that they will never achieve this support then the bill should be dropped immediately.

    As a Lib Dem I would urge Clegg to publiclly advise Cameron to drop the bill. The Tories could then blame the u-turn on the LDs which would lessen any negative affect related to a u-turn and meanwhile the Lib Dems (especially Nick Clegg) could well gain the trust and support of those voters who have left them in droves.

  45. Aahhh. I pressed the submit button too early and cut myself off in my prime. What I was going on to say was this: –

    As a rule of thumb, I’d always be sceptical of politicians who bemoan a lack of presentational skills as the reason for a policy falling apart. It’s much more likely that the policy is a turkey and the public don’t like it, not because they don’t understand it, but because they understand it all too well! If it walks like a turkey and looks like a turkey, it probably is a turkey, and no amount of dressing up can disguise it!

    Have the Tories forgotten all the lessons they learnt from the Poll Tax fiasco? I remember many a Tory spokesman back then saying that the electorate would swing behind it when they understood what it was really all about. Ironically, the more the electorate understood, the less they liked it and down the tubes it went, taking the Blessed Margaret with it!!

  46. Peter Bell

    You are right. If that is so obvious to you, what do you think is the chance of it happening?

  47. @ Old Nat & Hannah

    I’m impressed by your cultural sensitivity, but the term is actually Scotch mist, like Scotch whisky, and Scotch beef.
    I think Hannah probably knows it’s Scotch mist, she was quoting Roly Poly at 4.47pm.

  48. @Oldnat.

    That was a quote from Roly1.

  49. I think there is another interesting point here, that I’m sure Anthony Wells would agree with.

    It is this: it is true that voters in general never really came round to ‘trusting’ Cameron’s Tories with the NHS. The de-toxification never quite worked. In fact, this goes some way to explaining why David Cameron failed to win a majority at the 2010 election.

    And this is the point about why the NHS fiasco is damaging. Yes, it might not have cost the Tories a large drop in their current support… but what it does do is make it that much harder for them to win over the 2010 floating voters (the doubters) that never quite brought themselves to vote for them.

    In other words, the damage the Health and Social Care Bill has caused is primarily that it makes it even more likely that Cameron will struggle to get over 40% of the vote at the 2015 election. In this sense, the damage is a lost opportunity to gain the crucial votes needed to win outright next time.

  50. Hannah

    Sorry about that. Alas I hadn’t read Roly1’s post with the rapt attention it no doubt deserved (or at all actually). :-)

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