In the last few days a couple of people have asked about local government by-elections and whether we can tell anything about national levels of support from them, and I promised I would write a post about it. I have always been dubious in principle about whether local government by-elections can be used to gauge wider public support. The proportion of people who vote in them is vanishingly low and it seems likely that they will be strongly influenced by local issues, the personality of the candidates and the effort the local parties put in than the standing of the national parties. However, they are often put forward by people claiming to mean something, they are an expression of support and they do involve thousands of people a month, so I thought it worth crunching the figures properly and seeing if we can find a connection.

Local by-elections have, for many years, been carefully archived by Keith Edkins here, using the weekly info from the Association of Liberal Democrat Councillors. What I’ve done to test if we can do anything with local government by-election to predict actual elections is take the local by-elections in months running up to the last two general elections, and see if it is possible to build a model that predicts the general election result.

I can see two approaches to trying to relate local by-elections to national levels of support. We can either look at the average changes in the vote in local by-elections – who is on the up or down, or we can look at the aggregate shares of the vote and treat all the votes cast as akin to a big opinion poll.

Taking the changes in vote first, what if you take the average change in the vote for each party in each by-election and use that as a prediction? Obviously we can’t take whatever swing this produces and apply it to the last general election, since the dates don’t line up (if you had a by-election in 2004 in a ward last fought in 2003, you couldn’t apply the swing to the 2001 election, or you’d miss any change in support from 2001 to 2003). Instead we need a baseline for when the seat was last fought.

As many readers will know, Professors Rallings and Thrasher produce a notional figure for nationwide support at each local elections, which takes a large number key wards and projects them across the country. The soundest method I can find in theory, therefore, is to take the change in the vote for each party since the council ward was last fought, apply those changes to the notional nationwide figures from that set of local elections so you’ve got a projected national share of the vote for each individual by-election…then average them all. Unfortunately it doesn’t actually work.

In 2001 it would have given us CON 37% LAB 29% LDEM 30%
In 2005 it would have given us CON 38% LAB 29% LDEM 31%

In both cases it underestimates Labour, overestimates the Conservatives and grossly overestimates the Lib Dems. Of course, some local by-elections are obviously not good indicators. If Labour put up a candidate in a seat they didn’t contest last time, it doesn’t actually mean they have gone up by 15%. If a strong independent or minor party candidate suddenly stands, or ceases to stand, it have have a dramatic effect on the vote. By next plan therefore was to take only local by-elections where the 3 main parties had both stood at the by-election and at the previous election. I also tried excluding by-elections where a minor party had changed its level of support by more than 10 percentage points.

In 2001 (all three parties) CON 36% LAB 30% LDEM 29%
In 2001 (all three parties, little minor party impact) CON 35% LAB 30% LDEM 30%

In 2005 (all three parties) CON 37% LAB 34% LDEM 29%
In 2005 (all three parties, little minor party impact) CON 35% LAB 32% LDEM 29%

As you can see, its a bit closer, but still bears very little resemblence to the actual general election results. In both cases it underestimates Labour support and grossly overestimates Liberal Democrat support. All this suggests one of two things. Either Labour are disproportionately bad at getting their supporters out to vote in local by-elections, while the Lib Dems are disproportionately good OR lots of people who support Labour at national elections vote Lib Dem in local by-elections.

Once we know that though, can we factor it in and make a model based on local by-elections? If the bias against Labour and towards the Lib Dems was constant, maybe we could – at the crudest level we could take 10 points off the Lib Dems and add it to Labour! But as we’ve seen, in 2001 it was about 10 points, in 2005 it was about 6 points. Using this method even the movements in the projection don’t reflect changes in General elections support – from local by-election result’s we could have predicted that the Lib Dems would do *worse* in 2005 than they did in 2001, when actually they increased their support by 4 percentage points. Labour were doing better in local by-elections in 2005 than they had in 2001…yet their support fell 6 points at the 2005 general election. A model based on change in support in local government by-elections therefore seems to be a non-starter.

So, what about the superfically cruder method of adding up all the votes and looking at the shares?Where by-elections happen is, of course, random, so it is possible that the luck of the draw will produce by-elections all in safe Labour wards, or all in Tory wards. However, normal probability means it won’t normally happen. With a decent sized sample of by-elections we should have a good spread across the country.

Starting at the simplest level, if you take the total of all the votes cast in those elections then it certainly doesn’t reflect the levels of support in the general election. In 2001 it showed the Conservatives winning, in 2005 it showed Labour in third place. Any method must be more complex that that. If again we take only contests where all three of the main parties stood, the results are:

Sum of local by-elections Jan-May 2005: CON 33%, LAB 26%, LDEM 31%
Actual general election result 2005: CON 33%, LAB 36%, LDEM 23%

Sum of local by-elections Jan-Jun 2001: CON 32%, LAB 30%, LDEM 26%
Actual general election result 2001: CON 33%, LAB 42%, LDEM 18%

Sum of local by-elections Jan-May 1997: CON 28%, LAB 37%, LDEM 30%
Actual general election result 1997: CON 31%, LAB 44%, LDEM 17%

The Conservative support in local by-elections here isnt actually that far off, but Labour are once again underestimated and the Lib Dems grossly overestimated. Neither, alas, is there a steady relationship between the two sets of numbers – the Conservatives were doing 5 points better in local by-elections in 2005 than they were in 1997, but their vote at the general election was only two points higher. The Lib Dems did 4 points worse in local by-elections in 2001 than 1997… but increased their general election support. Here too, there really doesn’t seem to be any sort of strong relationship between local by-election results and general election performance.

None of this is new territory of course- Professor Rallings and Thrasher have been trying to crack this particular nut for many years, they’ve had some success at predicting local election results using it (though they’ve had some failures too) and did call the 1997 election right using it, but as far as I’m aware, they’ve never been able to get a model using local by-election results that consistently predicts general election voting intention – the simple fact is that Liberal Democrats always do better in local government by-elections than elsewhere, Labour always do worse, but the amount Labour do worse and the Lib Dems do better isn’t constant, rendering them of very little use in predicting general election support… unless you know better…

23 Responses to “Can local by-elections predict general elections?”

  1. Very interesting analysis, though your conclusion wasn’t a great surprise.

    I wonder if there’s any mileage in investigating the ‘anti-government’ effect in local elections? I have noticed over the years that (except when the government is popular, which is pretty unusual!), that there is a tendency for the government in power to do badly in local elections.

    For instance, if you extended your analysis further back, to when the Tories were in power, would we find that the Tories were underestimated and Labour overestimated by looking at local election results? I think that the LibDems would still continue to be over-estimated, as they have done disproportionally well in local elections for many years.

  2. @Anthony – what are the percentage of voters by main party at local versus GE in the cases you looked at?

  3. @PeteB – exactly what I was thinking. It would give a very useful indicative figure for the opposition (any of them)

  4. To be honest I don’t think there is a direct link from election results PER SE.

    BUT I do wonder if the presence or absence of local Councillors does have a substantial impact on the morale of the parties at the succeeding GE and therefore on the likely result..

    Does anyone else agree or am I just imagining this effect in the past?

  5. I think better not to try to work it out as you will remain confused!
    You have to factor why person no longer standing i.e. death, scandal, left in fit of pique, sack by standards etc etc and also whether outsiders suddenly join the fray!
    Just follow average of the now accurate polls!

  6. I recall work a long time ago which suggested that a change in government resulted in a 5% swing against the new government party in local council elections for any given level of national support.

    This seems consistent with the view that supporters of opposition parties are more likely to vote than those of a government, particularly when the government is in various stages of unpopularity. I also think that those whose Council Tax is a higher proportion of their expenditure are more likely to vote and this would give a bias to the Conservatives in recent years.

    I would be surprised if you did find a mechanistic relationship between local council by-elections and General Elections because of all the varying factors impacting upon these local elections. Nevertheless, I wonder whether you agree there may be a correlation with the direction of travel in the by-elections, ie who’s up and who’s down compared to the previous results, over a sufficiently large sample.

  7. David D – councillors are very often the people who do the donkey work of leafletting, canvassing and so on, so I’d be amazed if there wasn’t that sort of effect.

  8. Thank you Anthony,

    In the circumstances if Labour does as badly in this year’s local elections as the polls suggest, then does this not imply that the long established differential turnout could increase and potentially outweigh the electoral seat bias which has acted in their favour?

    I say this because I wonder how far the current polling projection formulae do and/or will take into account this situation.

  9. Here are the Scottish stats from last year (12 local by elections). We have not had any local by-elections in Scotland yet this year, although 3 are pending (Dundee – 12 March; Aberdeenshire and Highland – 23 April)

    Total First Preference Votes in Local Government By-elections in 2008
    (Change from local elections May 2007 in same wards)

    SNP 36.2% (+6.4)
    Lab 31.9% (-4.4)
    Con 14.1% (+0.2)
    LD 7.2% (+0.6)

  10. Very interesting. I was going to ask exactly this question the other day but didn’t because it seemed like asking for too much work. As you’ve done it anyway though … really illuminating and sort of confirms what I expected (I voted for two Lib Dem and one Conservative candidate at the last locals, purely because the individual councillors are excellent and I don’t care what parties they are from).

  11. Anthony said:
    “David D – councillors are very often the people who do the donkey work of leafletting, canvassing and so on, so I’d be amazed if there wasn’t that sort of effect.”

    I wish!!

    In my constituency, they are notorious by their absence! They all have strong opinions on WHAT should be done, HOW it should be done, WHAT the leaflets should look like etc…

    but when the actual foot slogging takes place…the tumbleweeds are more in ecidence than the councillors!

  12. @James – I wish I could cast 3 votes – in fact we should start to have phone voting at the next GE. We could televise the event for charity (comic relief seems ideal) and we could watch simon cowel judge potential candidates the the public could vote for :-)

    Just as with Xfactor they could throw in the ones we all know will win and a selection of complete nutcasses who just don’t realise that politics isn’t for them.

  13. I look forward to seeing you on the box then Keir.

  14. BNP polled 41%, way ahead of any other party, in Swanley Sevenoaks yesterday

    so just as well local elections don’t reflect general election results.

  15. @John T T – Whatever do you mean :-)

  16. Odd that my friend Mark Sneior hasn’t commented on this yet.

    Thanks for the research Anthony. :)

  17. One of the key factors in lower Labour turnout at local elections as well as by-elections is demographics. There many some marginal (currently Tory-held) council seats across the urban West Midlands which vote 2:1 Labour in general elections. Local activists will tell you that, come the general election, it is the ‘on benefits by choice’ residents who do not vote in local elections who turn out for Labour en masse.

  18. Local by-elections indicate that at the moment they show the Tories don’t seem to be doing as well as polls suggest.

  19. I think that on this site we tend to overlook two issues before trying to aggregate local by-election results to estimate the current state of the parties nationally.

    1. Local by-elections take place for authorities with differing responsibilities. To state the obvious, people are more likely to change their votes e.g. because of the qualities of the candidates standing, in partish or town council by-elections than those for county councils or large unitary authorities. The more local the election, the less good it is likely to be as a guide to national party standings.
    2. The salience of national issues as opposed to ideosyncratic local ones varies greatly from place to place. For instance, in general my experience is that the swing is more likely to depend on the individuals standing in more rural ares with a lower turnover of electors than in more amorphous cities. And to some extent things just depend upon local political culture. For instance the South Wales valleys, whilst until recently overwhelmingly Labour at General Elections, were always quite prepared to vote for independents. Plaid or even the Communists in local by-elections (admittedly, recently they seem to have adapted this philosophy to some Regional and Westminster elections too).

    One of the most valuable aspects of this site is that contributors often report not only the results of by-elections within individual consitutencies, but also their causes and issues arising. These observations can be used to adjust, WITHIN INDIVIDUAL SEATS, predictions made from national polling as to what the swing will be, and hence who will win the seat.

    Interpretation of local by-election results by psephologists would be greatly facilitiated if the pollsters conducted, on the lines of the poll last Autumn, a large scale survey of Westminster voting intentions at the time of the ordinary council elections, using samples large enough to predict for individual seats (at any rate marginals). More generally, given the number of polls recently that have produced similar results, this would fit a suspicion I have that we would get better value if the pollsters conducted fewer surveys but with sample sizes enabling more detailed analysis.

    P.S. Whilst I no longer belong to a party, I have sympathy from past experience with Anon Activist’s observations about some councillors who do not slog around the streets, although this only applies in a minority of cases.

  20. I think they need to be taken with large pinches of salt.
    They clearly deviate much more, even from local elections that are held at the normal time with the rest of the council.
    Some council by-elections clearly operate on a kind of mid-term protest against the local authority.
    The key is to aggregate enough results, and to use some non partisan judgement about the kind of places which are likely to vary more.
    I’d have thought those figures for early 1997 (30% LDs in council by-elections) should warn Lib Dems not to keep expecting to wipe the floor on the basis of a couple of council seats.

  21. Wolf – it’s comments like that that caused the article in the first place which can, I think, be summarised in four words: “Shut up, Mark Senior”. :)

  22. Just goes to show how totally artificial our system is for general elections and how far the results it produces differ from the reality of what people want. You can have 35-40% of the vote and win everything in a general election. Totally rubbish.