Hearts and Minds 2: Gaming PR?

Proportional Representation is supposed to ensure that the seats gains is roughly in proportion to the voting support and eliminate the need for tactical voting.  Some systems are rather better at this than others. 

I'm not a great fan of tactical voting : I'd rather people vote according to their beliefs and that this was represented fairly.    But as I've argued in Part 1: Vote for what you believe in

maybe an SNP- Green partnership would, for once, reflect the actual desires of most people. 

2011 Election

2011 Votes and seats

It so happened that in 2011, the SNP won a clear majority of seats, 69 out of 129, 53% on just 44% - 45% of the vote.   That wasn't particularly outrageous - Labour won 43% of the seats on 33% of the vote in the first elections to the Scottish Parliament in 1999.  But it's worth noting that the system is only roughly proportional.    This lack of proportionality is a result of there being only 7 top up additional members in each Region.  As its perfectly possible for one party to dominate a region, they may win a disproportionate number of constituency seats to the level of popular support - but also get top-up seats from a region where their support is weak. 

2016 Prediction

Since 2011, the constituency level of support for the SNP has grown and now runs as some 49% (March 2015) as demonstrated at the General Election performance of 50% of the vote, winning 56 of the 59 seats.  The SNP are therefore on target to win the vast majority of constituency seats in 2016.

2016 prediction based on YouGov poll, March 2015

As you can see, the rough proportionality more or less works.  The SNP, on about the same Regional Vote (43%) gains 69 seats.  They are not the same seats : there are more constituency seats and fewer regional top up seats and the decline in the Labour, and LibDem votes is reflected in fewer seats, with the Tories showing a modest increase and the Greens replacing the LibDems as the fourth party of Scottish politics in terms of both seats (8, 6% of seats) and votes (8%). 

Gaming the system

But with the SNP gaining most of the constituency seats, some have suggested that it would be possible for voters keen to see a strong showing for the pro-independence parties in the Scottish Parliament to game the system.  Those confident that the SNP can more or less, take the bulk of the 73 constituency seats (67 is the figure on a 49% constituency vote), could, the argument goes vote SNP in the constituency vote and for another pro-indy party in the Regional Vote.  

The logic runs, that if the SNP win few or no top-up regional seats, then those 43% voting SNP on the list are throwing their vote away and helping the unionist parties to win more top up seats.    

So what happens if SNP supporters split their vote between SNP on constituency and Greens for the List?  Let's shift 10% so the SNP are 33% on the Regional List and the Greens are on 18%.   

Gamed prediction - if SNP voters split their votes between SNP Cosntituency and Green on the Regional List.

On these figures, the SNP lose a seat overall - but the Greens gain 9 overwhelmingly at the expense of all three unionist parties.    The pro-Indy balance in the Scottish Parliament would be 85 to 44 seats. 

Now, a lot can happen between now and the Holyrood elections in 2016, but if you a voter wanting to see a clear pro-Indy majority at Holyrood and are, like many, broadly favorable to both SNP and Green policy (see Hearts and Minds 1: Voting for what you believe), then there is a clear path ahead.

No Party is going to advocate this and indeed you can expect the SNP to be very vocal in asking their supporters not to risk their seats by splitting the vote.   And the Greens officially are unlikely to ask supporters to support the SNP in the constituency vote and Greens on the Regional List.  That's politics - we have a long tradition that is hard to break of parties being unwilling to co-operate outside single issue campaigns.  So it's up to individuals to make their own minds up and tell parties what they want to happen.

The difference between the support for parties in the constituency and Regional List Votes shows we have a remarkably sophisicated electorate.  They have shown themselves willing to support the SNP in constituencies, where they are likely to win.   But the SNP's underlying level of support is lower and the public know it and are willing to promote the plural multi-party politics that the a feature of most of northern Europe.    Let's join them!


I'm of course a partisan in this, so do try out the scenarios for yourself.  The notes below show the data I used from the opinion poll and I'll try to remember to add new polls as they are published.  And you can use the same model I did and see the results. 

Notes:

Voting intention data
YouGov for Sunday Times, 12th March 2015
http://cdn.yougov.com/cumulus_uploads/document/2i4cik3x8y/Times_Scotland_150312_Website.pdf

Seat prediction
Scotlandvotes.com (Sponsored by Sunday Times)
http://www.scotlandvotes.com/holyrood