A wee flashback as an appetizer
About two weeks ago Survation released a comprehensive poll of Scottish voting intentions. I have already covered the parts about the General Election and the Independence referendum. Now let's have a look at the part about Scottish Parliament. Constituency results are pretty good for the SNP who are at their highest since September 2017. Regional list results on the other hand are far less satisfactory with a higher than usual proportion of voters switching to Scottish Greens. I have a hunch that the (wrong but widely held) belief that the list vote is a second preference is the most likely explanation here.
Survation publish their findings with one decimal place which is kind of irrelevant when the sample size is about 1,000 so the margin of error is about 3%. But it's their choice and I respect it. Another interesting part is that the Conservatives would fall to third place on the regional list vote 'thanks' to an unusually high UKIP vote.
Another interesting aspect of this poll is that it is a textbook case of how different approaches to modelling seat projections will lead to slightly different results. I compared the seat projections using ScotlandVotes (to my knowledge the only website that features Holyrood seat projections from polling data) to those using my own model. First here is what ScotlandVotes delivers.
So we have the SNP down four seats but pro-Indy majority bags 69 seats as in 2016 thanks to the Scottish Greens' surge. Labour are back to second party and UKIP get no seats. And now here is what my own model projects.
The SNP are still down four seats but pro-Indy majority gains one seat. Labour is still back to second place but here UKIP manage to gain three list seats (Highlands and Islands, Mid Scotland and Fife, South Scotland). This is the direct result of how ScotlandVotes' model and mine handle the list seat projection differently.
A wee smitch of PsephSpeak you're allowed to skip but might want to read anyway
ScotlandVotes rely on straight Uniform National Swing (UNS). Think of UNS as a 'flat rate' swing. Votes in every electoral division (constituency or region) move in the same direction by the exact same amount. It is the most ancient prediction method and the most commonly used by psephologists. It is reasonably accurate when applied to a large number of seats (like House of Commons projections) as outliers tends to cancel each other out.
In my Holyrood model I chose not to apply straight UNS to the list vote across all regions but instead to calculate individual sets of voting intentions for each region. I use straight UNS when the pollster does not provide a crosstab of voting intentions by region, which is the case with YouGov or Panelbase. When the pollster provides such a crosstab, as Survation do, I use their data instead.
In this specific case, UNS based on a 4.7% national average doesn't take UKIP in any region over the implicit »6.5% threshold built into AMS to bag a list seat. Though they would come pretty close in Highland and Islands. The Survation crosstab has UKIP over the threshold in three regions, and so you get UKIP sitting in Scottish Parliament for the first time ever. See Table 19 on page 22 of the Survation report.
For the record I don't use straight UNS for my First Past The Post (FPTP) seat projections either. I use a mix of UNS and Proportional National Swing (PNS). Both are explained in layman's terms on this Canadian site. Currently my FPTP model is tuned to 70% UNS + 30% PNS which seems a reasonable compromise to approach what would likely happen in an actual election.
Anyway minor methodological differences shouldn't make us overlook the true political significance of this poll. Whatever the approach, an actual election delivering the same results would be a major success for the Yes movement. Pro-Independence parties would hold their majority and possibly even strengthen it. The Scottish Government would have a renewed mandate for a second independence referendum (if it hasn't already happened and been won). And the SNP would get their fourth consecutive term, a major achievement even if they would have to content themselves with being a minority government again.
And now where does the polls' trend take us?
Of course the average of recent polls tells a different story than the Survation poll I discussed at length to give you the good news first. My current super-sample (four constituency polls and three regional list polls fielded in June and July) is less favourable for the pro-Independence parties. Super-sample size is 4,116 (1.48% MOE) on the constituencies and 3,098 (1.71% MOE) on the lists. Here is the current weighted average of voting intentions, with the detail of list votes by region:
Seat projections then. Constituencies by SLLM rating, list seats by region, full Scottish Parliament. Despite the good results from the Survation poll, rolling average still delivers pro-Independence parties two seats short of a majority and Conservatives remain the second party.
For comparison I fed ScotlandVotes the same data and their model delivers very similar results. Despite the methodological differences noted above they too have pro-Independence parties in a minority on these numbers. There are also some minor differences in the overall distribution of seats but well within the super-sample's MOE.
Any alternate scenarios?
Right now six seats are projected to change hands. All from the SNP to the Conservatives. But it's not by any means a Conservative landslide as their margins is these seats would range from 0.8% to 6.5%.
We also have six marginal seats which, under the proper circumstances, could go either way. Five of the projected Conservative gains qualify as marginals but only one seat currently held by the SNP.
As I explained in my first post about Holyrood projections, it's difficult to build a simple Min/Max scenario here because of the odd way AMS works. Remember a change in constituency seats can result in a change in the other direction in the allocation of list seats, with the overall result remaining the same. This is the case again here with Angus South. If the SNP lost this seat it would automatically be 'compensated' by a list seat for the SNP in North East Scotland where they are currently projected to win none.
The other five marginals tell a different story as all are within regions where the SNP is currently projected to win no list seats. So if the SNP prevails in these seats it would have no impact on their number of list seats. The only consequence of the changes would be to reshuffle list seats among the other parties. This 'SNP max' scenario would deliver this result:
Even with Greens losing one list seat to the Conservatives in Lothian as a direct 'compensation' for the SNP holding Edinburgh Pentlands, pro-Independence parties would hold a two seat majority. Two seats down from the 2016 results but still enough for a renewed mandate for independence, if that hasn't happened already by 2021.
Seat breakdown by region:
What to expect next?
Recent polling for both Scottish Westminster seats and Scottish Parliament definitely show a surge in SNP voting intentions. Best educated guess is that next polls will show the same trend and confirm that a renewed pro-Independence majority in Holyrood is not only possible but the most likely outcome. Of course upsets can't be ruled out but I honestly don't expect any major shift away from the SNP, quite the opposite actually.
Anyway stay tuned for further updates.
Saor Alba gu bràth
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