Thursday, 16 May 2019

Fun with numbers - splitting the Remain vote at the MEP elections

The MEP elections in Great Britain, to be next held on 23 May 2019, use the d'Hondt system for allocating seats in each of eleven constituencies/regions.

Whether the Remain parties (Lib Dem, Green and Change UK) have shot themselves in the foot (feet?) by competing over the same small pool of voters is an interesting question.

Let's treat this as an unofficial In-Out Referendum and assume votes cast are in line with current opinion polls and are the same in each constituency, as follows:

Brexit Party - 31%
UKIP - 4%

Lib Dem - 10%
Green Party - 10%
Change UK - 10%

Undecided - neutral - ambivalent
Labour - 22%
Tories - 13%

The more seats there are in a constituency, the closer the result is to proportional representation; the fewer seats, the closer the results are to FPTP.

If you crunch the numbers (or use Paul Lockett's fine calculator) for the largest constituency with ten seats (South East), the end result is the same whether the Remain parties had put up a single list or not - Leave 4 seats, Remain 3 seats and Undecided 3 seats.

The difference is that with a single list and 30% of the vote, Remain would win seats 2, 5 and 9; with three competing Remain parties, they will win seats 7, 8 and 9. So they will do relatively worse in smaller constituencies and relatively worse overall.

The reverse is true for Leave, only not as markedly. If Remain had put up a single list, Leave would win seats 1, 4, 8 and 10 of a ten-seat constituency. With the Remain vote split, they will win seats 1, 3, 5 and 10.
To sum up, for various sizes of constituency with a split Remain vote, seats will be as follows:

3 seats = Leave 2, Undecided 1
4 seats = leave 2, Undecided 2
5 seats = Leave 3, Undecided 2
6 seats = Leave 3, Undecided 3
7 seats = Leave 3, Undecided 3, Remain 1
8 seats = Leave 3, Undecided 3, Remain 2
9 sweats = Leave 3, Undecided 3, Remain 3
10 seats = Leave 4, Undecided 3, Remain 3

As only five constituencies have seven or more seats, Remain have definitely messed up badly. With a single list Remain vote, seats would be as follows:

3 seats = Leave 1, Undecided 1, Remain 1
4 seats = leave 2, Undecided 1, Remain 1
5 seats = Leave 2, Undecided 1, Remain 2
6 seats = Leave 2, Undecided 2, Remain 2
7 seats = Leave 2, Undecided 3, Remain 2
8 seats = Leave 3, Undecided 3, Remain 2
9 sweats = Leave 3, Undecided 3, Remain 3
10 seats = Leave 4, Undecided 3, Remain 3

Just sayin'...


Dinero said...

Interesting subtlety. I noticed that in the local elections many councils only had one third of their seats up for election and the media coverage was not acknowledging that fact.

Mark Wadsworth said...

Din, each council has a slightly different system, you can't expect MSM to cover all the subtleties, it's the overall picture and trend that count.

Dinero said...

I was acknowledging the subtly of your observation.

As for my observation, the point is, the media was reporting changes in councils overall control as if the councils themselves were up for election, and that by their reckoning it was a direct measure of sentiment to a general election, when in fact with only one third of the seats contested, and it is not known what party the vacant seat was previously occupied by, it is not a direct tally.

Mark Wadsworth said...

Din, the MSM reporting gains and losses by party, do you think that's misleading?

Dinero said...

Yes it is misleading when the MSN talked about parties wining and loosing for two reasons. A ward has three seats and an individual councillor has a four year term and then has to stand again. And those terms are not synchronised. And so when the MSN says a party has lost its seat and the others did not, that may actually be because only one seat is contested each year and the other councillors of the other parties were not up for election that year. And it is misleading when the MSN talked about a party "Holding or" "loosing" a council as if the public were voting on all the seats when in fact only one third of its seats are contested each year.

references to the thirds and halves

Mark Wadsworth said...

Din, some wards have three seats. But where I live, wards are smaller and have one seat. You can't generalise about these things.