Thread by @MartinJKeatings

@Lovingi79716481 I can explain it for you now if you like. It's actually more simple than the politicians make out.

@Lovingi79716481 First thing - stop thinking of it as d'hondt, because it's not. Sorry, but it really annoys me people call it that - it's the additional member system. Now for this example I am going to use my region mid Scotland and fife.

@Lovingi79716481 So! We have the region MSF (mid-scotland fife). It has 9 constituencies in it. The 9 constituencies form the region. First we have the constituency ballot where you vote for the person. In MSF 120,000 people vote SNP.

@Lovingi79716481 Around 70,000 vote Tory, 50,000 vote Labour. The SNP take 8 out of 9 constituency seats. It's first past the post in those constituencies (most votes win).

@Lovingi79716481 Now remember that number 8. That's reeeeeeeeally important.

It comes time to count the regional ballot. See the number of votes above.

@Lovingi79716481 Now what you have at the start of the count is the SNP on 8 seats in the region. You have labour and tories on zero. So straight out of the gate we need to establish what is called "the divisor" which is just a fancy way of saying "how much do we divide their votes by on the list

@Lovingi79716481 And that's worked out by taking the number of seats a party already has and adding one.

For the SNP, they have 8 constituency seats so their divisor is 8+1 = 9

@Lovingi79716481 Labour and the Tories have zero seats in the constituency and so their divisor is 0+1=1

@Lovingi79716481 These are the numbers that the votes on the regional ballot are first divided by so:

SNP = 120,000 votes - We divide that by 9 which gives us 13333

As for lab and tories, that's 70,000 divided by 1 and 50,000 divided by 1. Which is obviously still 70,000 and 50,000

@Lovingi79716481 So straight away the SNP are penalised 9 times more than the Labour and Tories.

After this first division. The tories clearly have the most votes 70,000 vs 50,000 vs 13333

@Lovingi79716481 So the first seat on the list goes to the tories. They now have 1 seat so their divisor is recalculated 1 seat + 1 = 2. So we take their 70,000 votes and divide by 2. That now drops them into second place at 35,000 behind labour.

@Lovingi79716481 So! Labour now have 50,000, tories have 35,000 and the SNP are still at 13333. Now labour are at the top - so they get a seat. They now have a seat so we recalculate their divisor. 1 seat + 1 = 2. So we divide their 50,000 by two. Now the tories are back in the lead...

@Lovingi79716481 So we give them a seat.

So! The long story short in Mid Scotland and Fife is that we end up with 4 tories and 2 labour MSP's

@Lovingi79716481 With 8 seats the SNP get penalised 9 times more than anyone else. If they took willie rennies seat in the constituency ballot as well, well now we're talking about them getting penalised 10 times as much.

@Lovingi79716481 In order for the SNP to take just 1 single seat in the list they'd need at a minimum an additional 46,000 votes in MSF, which is not going to happen. You're talking nearly 1/3 of the unionists voting SNP.

@Lovingi79716481 If they took rennies seat and were penalised 10 times as much, they'd need an additional 80,000 votes over and above the 120,000 votes they already have.

@Lovingi79716481 The system was designed a bit like a set of scales. If one ballot goes up, the other penalised you to make the other side go down. There's only a very very small avenenue in the middle where both sides of the scale are equal where one party can get maximum votes.

@Lovingi79716481 But to hit that (like 2011) the SNP would actually need to lose votes in the constituency ballot so they wouldn't be so heavily penalised in the regional list.

Hope that helps.

@Lovingi79716481 Theres only two area where the SNP might and I stress might get a seat in the list, south of Scotland and highland - that's because they are less popular on the constituency ballot.

@Lovingi79716481 But even with that, its still nowhere near what another party could do and this is where ALBA comes in.

Remember these words - if you don't stand on the constituency ballots, when the count starts for the regional you have no seats.

@Lovingi79716481 If you have no seats, your divisor can only be 0+1=1, ergo you don't get penalised. Which means ALBA, would be on the same terms as labour and the tories vote wise. A 50% shift of SNP voters voting Alba in the regional ballot...

@Lovingi79716481 ...which isn't detrimental to the SNP (because remember there are 73 seats in the constituency ballot, 56 in the regional) because they're expected to get their majority of 65 on the constituency ballot - but a 50% shift in the regional ballot to ALBA...

@Lovingi79716481 ...could see us wipe out up to 24 unionist seats. And this is the important bit.