Lord Ashcroft put out a new batch of constituency polls today, this time revisiting some Conservative -vs- Labour marginals that were very close the last time he polled them. The average swing across the seats polled is 4.4 from Con to Lab, the equivalent of a two point lead in a GB poll. This is obviously bigger that the position in most national polls, but I suspect it’s more of an England effect than a marginal effect – all the seats polled by Ashcroft were in England, and because of the collapse of Labour in Scotland the Con>Lab swing in England is actually bigger than in GB as a whole. Full details of the polls are here.

Most of the seats Ashcroft polled showed results that were pretty similar to the last time he polled them at the tail end of last year, with changes well within the margin of error. The only big shifts were Labour doing much better in Chester than before, the Conservatives doing much better in Worcester than before, and Labour doing much better in Southampton Itchen. I expect the last one is just a reversion to the mean after the previous Southampton Itchen poll produced figures that stuck out like a sore thumb – this poll showed a fairly typical swing in the seat, when Ashcroft’s previous Southampton Itchen poll had shown a very dubious looking swing from Lab to Con.

TNS also released a new poll today with CON 33%, LAB 32%, LD 7%, UKIP 17%, GREEN 4%, OTHER 7%. TNS typically show a significantly larger Labour lead than other pollsters, so the small Tory lead is slightly surprising. It may be a methodology effect – TNS seem to have dropped the weighting by European vote that they introduced earlier this year (though its introduction didn’t seem to make much difference, so its dropping really shouldn’t), and have started reallocating UKIP and Green supporters in constituencies that don’t have UKIP or Green

Finally, tonight’s YouGov poll for the Sun has topline figures of CON 34%, LAB 36%, LD 7%, UKIP 12%, GRN 6% – so a couple of Labour leads from YouGov so far this week. For the record, today’s poll has Labour at their highest this year, UKIP at their lowest this year… but of course, all the normal caveats apply, don’t get overexcited about individual unusual polls, watch the trend across all the pollsters.

Two types of outlier

This morning TNS released a new poll showing figures of CON 28%, LAB 35%, LDEM 6%, UKIP 18%, GRN 7% (tabs). The seven point Labour lead is striking, and out of line from the broader trend. Usual caveats apply, but for once I haven’t seen many people over-react to it. Most have sensibly enough seen it as the just the other side of the coin to the ICM poll earlier this week showing a solid Tory lead – two outliers in opposite directions. However, it is worth looking at the different reasons why these two polls went against the trend.

On average ICM produce figures that are slightly more Con/less Lab than average, but only by a tiny bit, generally they show Labour -v- Tory leads that are much the same as those from other companies. The reason that their poll on Monday showed a four point Tory lead when other companies are showing the race almost neck-and-neck is almost certainly just random sample error. Samples vary from day-to-day, month-to-month and sometimes you get one that’s a bit Laboury or a bit Conservativety in ways that weighting does not correct. I expect ICM’s next poll will be in line with those from other companies.

TNS is a different sort of outlier. The seven point Labour lead may be different from that shown by other pollsters, but its actually in line with TNS’s previous polls. In their previous four polls they showed Labour leads of 6 points, 0 points, 7 points and 7 points. Over on my chart of house effects TNS’s polls on average show a Labour lead three points larger than other companies (and if anything the gap is growing!) This isn’t random sample error, this is a consistent methodological difference between TNS and other companies, and unless they switch methods I expect their future polls will continue to show bigger Labour leads than other polls.

Two outliers, but one is probably just a random blip from a pollster who normally shows the same as other companies, one looks like a typical poll from a pollster who regularly produces polls that show a bigger Labour lead than the pack.


TNS Scottish poll

This morning TNS released a new Scottish poll. Topline Westminster voting intention figures are CON 16%, LAB 31%, LDEM 4%, SNP 41%, GRN 6%, UKIP 2% (tabs here). Under normal circumstances these would obviously be good figures for the SNP, but these are not normal circumstances and it’s a much smaller SNP lead than that suggested in recent polls by YouGov, Survation and Ipsos MORI.

Unlike their GB polls which are now done online, TNS’s Scottish polls are still done using face-to-face interviews. This means the fieldwork tends to take significantly longer, and the polls are then often not reported until a week or so later. The fieldwork for this poll was conducted between the 14th January and the 2nd February. This means the Survation and MORI polls from last month which showed 20 point and 28 point SNP leads for the SNP had fieldwork done at the same time as the start of this poll. The YouGov poll last week which had a 21 point SNP lead had fieldwork done at the same time the fieldwork for this poll was finishing (so is mostly significantly newer than this one!). What this means is that much of the reporting and headlines on this poll are just rubbish – the poll does NOT show the SNP lead falling. It shows a smaller SNP lead – this may well be for methodological reasons, or perhaps a bit of random sample variation, but given the respective timing of the fieldwork it cannot be that public opinion has changed since the previous poll showing a 21 point lead, as this poll was mostly conducted before that one. It’s a thoroughly bad idea to try and draw trends between polls conducted using very different methods anyway, but certainly check when the fieldwork was done and get them in the right chronological order.

Today’s daily YouGov poll for the Sun has topline figures of CON 34%, LAB 33%, LDEM 6%, UKIP 13%, GRN 7%. This is the first Tory lead from YouGov this week – their underlying average has the two main parties very close to each other, so we should expect normal random sample error to regularly produce both Labour and Conservative leads until and unless one party opens up a proper lead.

Also out in the early hours of this morning was a new TNS poll which has topline figures of CON 27%, LAB 33%, LDEM 6%, UKIP 18%, GRN 8%. It looks as if I may have rather jumped the gun when I said the methodology change in TNS’s last poll had brought their figures more in line with other companies, as this one seems to be back to their traditional pattern of showing a significantly larger Labour lead than other companies.

A quick update on the latest voting intention polls. This morning’s YouGov poll for the Sun has topline figures of CON 33%, LAB 34%, LDEM 6%, UKIP 14%, GRN 8% (tabs) – more typical figures than YouGov’s Tuesday poll.

There is also a new TNS poll with topline figures of CON 31%(+3), LAB 31%(-4), LDEM 8%(+2), UKIP 16%(-2), GRN 7%(+2) (tabs). Up until now TNS have tended to release their polls incredibly slowly, often a week or more after their fieldwork was finished, rendering them out of date by the time we see them. Fieldwork for this one however finished on Monday so it’s more timely than usual. The last couple of TNS polls showed Labour leads of 7 points, significantly and consistently larger than any other company. Today’s looks more like other polls. (UPDATE – thanks to those in the comments section who missed something obvious in the TNS tabs that I overlooked! TNS have always weighted by 2010 recalled vote, but they are now weighting by 2010 recalled vote AND 2014 European vote – whether or not this is responsible for their figures coming into line with other companies’s is unclear.)

Finally Ipsos MORI put out their latest Scottish poll yesterday. Westminster voting intentions in Scotland were CON 12%(+2), LAB 24%(+1), LDEM 4%(-2), SNP 52%(nc), GRN 4%(-2). We’ve now had three Scottish polls conducted in 2015. The first one from Panelbase showed the SNP dropping four points and raised some speculation about whether their huge post-referendum surge was fading away again. The second from Survation also had the SNP down, but only by two points and this one from MORI has the level of SNP support holding steady. (On top of that, when tables for the Panelbase poll appeared it turned out that the voting intention question wasn’t asked first, it was asked after a question about whether or not falling oil prices damaged the economic case for Scottish independence, so the SNP fall in that first poll may be a question ordering effect rather than a genuine change)