seocan Wrote:
Central Scotland; SNP won all 9 constituency seats.
The regional vote was 129k for SNP, 67 for labour and 43 for Ruth. Labour gets 5 seats , tories get 2.
What is the maths behind the adjustment? Thats an overwnelming win in the regional vote for the SNP yet they get nothing.
Any ideas?
It's a repetitive process until each of the 7 regional seats are filled. For each iteration the votes per party on the regional ballot are divided by the total number of seats within the region (both single member constituency and already allocated list seats) + 1.
Thus on the first iteration the maths is as follows:
SNP 129,000/(9+1) = 129,000/10 = 12,900
Labour 67,000/(0+1) = 67,000/1 = 67,000
Tory 43,000/(0+1) = 43,000/1 = 43,000
So Labour got the first list seat allocation.
Next iteration:
SNP 129,000/(9+1) = 129,000/10 = 12,900
Labour 67,000/(1+1) = 67,000/2 = 33,500
Tory 43,000/(0+1) = 43,000/1 = 43,000
So the 'Ruth Davidson' Party takes the second allocated seat on the list....
The regional ballot does not allocate seats proportional to the regional vote, it's a corrective measure to the inevitable non proportionality of the first past the post constituency results.
The SNP effectively 'broke' the system in 2011, they hit the sweet spot in terms of constituency seats and regional vote balance. This year the SNP did better in the constituency vote and ironically that enabled the corrective measure of the d'Hont system to actually work as intended and pull back the imbalance. In effect each constituency seat gained across Scotland cost the SNP 2 list seats. The SNP were just short of a majority of votes and came out just short of a majority of seats, so the system has worked pretty much as intended.
