The good news for Labour in its local elections underperformance

Welcome to the 107th edition of The Week in Polls, which comes with an unashamedly clickbait headline. But after some data and graphs, I hope I’ll convince you the headline is also justified.

Then it’s a look at the latest voting intention polls followed by, for paid-for subscribers, 10 insights from the last week’s polling and analysis. (If you’re a free subscriber, sign up for a free trial here to see what you’re missing.)

But first, a quick plug for Tom Carver’s piece in The Times, What are the odds of a hung parliament — and would it help the Tories? which is only marred by quoting myself.

---

Been forwarded this email by someone else? Sign up to get your own copy here.

Want to know more about political polling? Get my book Polling UnPacked: the history, uses and abuses of political opinion polling.

---

Why Labour should be happy with its underperformance in the local elections

The local elections - determining who is in control of large parts of local government, with significant responsibilities, budgets and headcounts - matter in their own right. But as this is a newsletter about polling, let’s look at what the results mean for the polls and see if we can put some substance into that clickbait headline.

First off, what underperformance?

As I wrote last week:

It’s notable that Labour consistently underperformed the predicted [council seat] gains. The question of why is one of the more useful things to dig into than some of the eccentric ‘these results show the Conservatives could win the general election’ claims.

But what’s got much more attention is Rishi Sunak’s claim the local elections pointed towards a hung Parliament, as the Labour lead in them was much lower than in the general election voting intention polls.

That view of the PM’s has taken quite a battering from the expert, such as Ben Ansell (whose newsletter you really should sign up to) and Peter Kellner (whose blog really should be on your must read list).

But simply bashing the Prime Minister for over-exuberantly hunting for good news is easy. So let’s to a further - and show you why the very same figures that the he has been citing are actually good news for the Labour Party.

Step one is to look at the national vote shares in the local elections. Simply adding up the votes cast is¹ not helpful for comparisons over the years as different places are up for election each year. So what the experts do is to extrapolate from those places that are up for election to what the vote shares would have been if the whole country had had local elections. There are two ways of doing this, done by two different teams and using different data sets. Handily, both teams (John Curtice, Stephen Fisher and the BBC with their PNS calculations, and Michael Thrasher, Colin Rallings² and Sky with their NEV calculations) come up with very similar figures, which can give us more confidence in them.

But they are still just that: an extrapolation of national vote shares in council elections using that May’s local elections. In particular, they have three limitations.

Two are technical. If one part of the country has no local elections and if the politics of that part of the country may be changing differently to the rest of the country, then the extrapolation is at risk. Such variations on a significant scale are in fact fairly rare, but the absence of any Scottish data from these local elections is a risk factor this time around.

Moreover because the geographic spread of where is up each year varies quite considerably, it may be that a party which is - say - particularly strong in some parts of the country that are disproportionately over-represented in that year will see its PNS/NEV inflated as a result. There are hints of the flip version of that this year, which was the year in the four-year cycle where (despite all the variations over time in what is up in what year) the Lib Dems consistently contest a lower proportion of seats than in other years. That suggests that this year was therefore generally fought with weaker grassroots organisation for the party than in other years. So you should expect a lower PNS/NEV than would occur if other years in the cycle - i.e. stronger organisation - had been up. There is a hint of such a cycle in Lib Dem support, although the data points are few and the changes slim.

Then there is the big political limitation: PNS and NEV are about voting in local elections, with different turnout, tactical situations and personal votes than for general elections. People do not vote the same in local and general elections.

This final point is at the heart of most of the Sunak bashing. Yes, Labour was ‘only’ 8 points ahead (average PNS/NEV figures) of the Conservatives but that doesn’t mean the national polls showing them much further ahead are wrong.

Even so, that 8 point lead was significantly down on the 15 point lead in the 1996 locals, ahead of the 1997 general election. That, plus the seat numbers point I opened with, are legitimate reasons to talk about a relative Labour underperformance, even if the figures are not good enough to justify the PM’s claims.

There have been some explanations given, which reinforce the point that the underperformance isn’t, with an eye on the next general election, something to worry Labour about. Such as that they suffered to independents in areas with particular concentrations of Muslim voters. But, as Rob Ford regularly points out, those are generally areas which Labour are likely to win comfortably at a general election, and certainly not at risk of losing to the Conservatives. Therefore this doesn’t matter much for hopes of getting to 10 Downing Street.

I think though, armed with data, we can go further than that and find positively good news for Labour in that underperformance.

That’s because of the history of under and overperformances at local elections. The following graph compares the local election score for a party (PNS/NEV average) with its standing in the opinion polls in the run-up to the local elections.³

Here is the history of Conservative, Labour and Lib Dem over and underperformances:

Note the consistent overperformance of the Lib Dems in local elections compared with the polls. Go Team Bar Chart.

Note also the overperformance of the Conservatives in local elections under William Hague (1997-2001) and the massive Labour underperformance in those years. Yet Labour following up its landslide win in 1997 with a nearly as large win in 2001. Underperformance is not itself a harbinger of general election doom.

So here is a different way of looking at the over/under: comparing Labour’s over/under score versus its poll standings at the time.⁴

With some noise, the picture is still clear: the better Labour is doing in the polls, the worse its local election underperformance becomes.

And that means… a big local election underperformance is what you’d expect if Labour is riding high in the polls.

And that is exactly what we got this time around. 44% in the polls, 10 point underperformance, pretty close to the trend line through those data points.

Which means that Labour’s underperformance is a sign that its high poll ratings are right.

It was the same story last year (44% in the polls, 9 point underperformance).

So these locals, as with last year, show the polls are likely to be right.

That’s good news for Labour.

There that wasn’t so clickbaitingly outrageous after all, was it?

A more straightforward piece of analysis by Will Jennings, comparing NEV scores with subsequent general election results, also shows that this May is not a pointer towards the polls being wrong. Similarly, Paul Whiteley’s modelling of local election results versus subsequent general election results point to a Labour majority (though a small one).

There are a few nuances it’s worth adding as a postscript. One is that getting a local election in line with the national polls is not only good news for Labour in itself, but also even better news when you remember that the poll average is one of all the pollsters, not just those who are currently showing the lowest Labour scores. If anything, the locals yardstick suggests those pollsters are on the low side with their Labour scores.

Bad news too for the Conservatives in that the swing, as spotted by Lewis Baston, seems to have been proportional rather than uniform. Proportional swing at a general election would be unusual and would mean a worse seat count for the Conservatives. These locals therefore give a bit of extra weight to expectations of a seat meltdown for them. (More on proportional versus uniform swing questions in my guide to MRP polls.)

One consolation, though, for the Conservatives. Andy Lawton’s analysis shows that the Mayor polls under-stated the Conservatives by 1.5 points and over-stated Labour by 1.75 points. But knocking four points or so off the national poll leads still doesn’t get them close to being in contention.

---

National voting intention polls

The polls are both all the same - big Labour leads - and also all over the place - big variations in the size of those big Labour leads.

I may return to this in more detail in a future edition. For the moment, the theories being floated on polling Twitter - one, many or none of which may be right - are around the different treatment of don’t knows by some pollsters, possible problems with past vote weighting and more broadly the difference between pollsters who try to capture public opinions as it now stands and those who lean more to predicting how people would behave in an election (e.g. do you take ‘don’t know’ at face value or model how such a person will behave based on past experience?) Some of those theories mean we can expert the polls to converge, but not all of them.

For more details and updates through the week, see my daily updated table here and for all the historic figures, including Parliamentary by-election polls, see PollBase.

---

Last week’s edition

Reality arrives: how did the polls and projections do?

---

My privacy policy and related legal information is available here. Links to purchase books online are usually affiliate links which pay a commission for each sale. Please note that if you are subscribed to other email lists of mine, unsubscribing from this list will not automatically remove you from the other lists. If you wish to be removed from all lists, simply hit reply and let me know.

---

(Only) a third think the Conservatives are extreme, and other polling news

The following 10 findings from the most recent polls and analysis are for paying subscribers only, but you can sign up for a free trial to read them straight away.