Alternative Vision: the multi-seat constituency version of the 2010 election.

In a previous blog I'd reported on the hypothetical result that would arise from applying an AV type vote to the results of the May 2010 election results for the NI constituencies. The other potential electoral system that might be employed in future is the multi-seater constituency where a single-transferable vote (STV) is used to select candidates. Under the first past the post system used in May 2010, the DUP won 8 seats, SF 5, SDLP 3, Alliance 1 and Independents 1. I'd calculated that, under AV, the DUP would still have taken 8 seats (although not the same 8), SF 5, SDLP 2, UCUNF 2 and Independents 1. Multi-seater constituencies would alter this quite dramatically, giving DUP 5, SF 5, SDLP 3, UCUNF 3, Alliance 1 and Independents 1.

As with the AV system discussed previously, the shape of the parties after the final count would have provided for a markedly different post-election story.

The main issue with introducting multi-seater constituencies is definition. For the purposes of the analysis, I've simply used three six-seaters. The alternatives were either to employ six three-seat constituencies (to make up the eighteen seats), or two four-seaters and two five-seaters. I decided against going with the smaller options, or uneven seats.

As for the geographic extents, the two obvious complications are whether to divide either east-west or north-south, and, how to incorporate Belfast. Without doing any runs on the numbers, I've separated the four Belfast constituencies and added North Down and South Antrim to form a rough Greater Belfast constituency. Arguably, it would make sense to include Lagan Valley or East Antrim instead. Since a portion of East Antrim was moved from North Antrim by the last boundary commission and the urban sprawl into North Down from Belfast is more or less unbroken, I went for these two instead. The remaining division was fairly straightforward as a rough north-south dividing line separates those south of the line (Fermanagh-South Tyrone, Upper Bann, Newry and South Armagh, Strangford, South Down and Lagan Valley) from the remainder.

Finally, a note on treatment of the Independents for the analysis. All but one were retained as individual candidates, although the only one with a significant vote (from a statistical point of view) was Lady Sylvia Hermon. As a former UUP MP, for transfer purposes, she was treated as a UUP candidate and, where necessary, split equally with UCUNF. As a candidate agreed by two parties, UCUNF and DUP, Rodney Connor was not included in the analysis. As such, his vote was simply split equally and added to that of the DUP and UCUNF.

First 'Greater Belfast'. Based on the combined votes of the various parties in the six constituencies, with a quota for election set in the standard fashion, the first count would see the number of quotas received by each party as: DUP - 1.6399, SF - 1.4029, UCUNF - 1.1646, SDLP - 0.9471, Alliance - 0.8453, Independent (Hermon) - 0.7345, TUV - 0.1810, Green - 0.0707, and, Ind (Macauley) - 0.0137.

Holding one quota each, seats would immediately go to the DUP, SF and UCUNF. At this stage, with three seats filled, the relative quotas for each party would be SDLP - 0.9471, Alliance - 0.8453, Independent (Hermon) - 0.7345, DUP - 0.6399, SF - 0.4029, TUV - 0.1810, UCUNF - 0.1646, Green - 0.0707, and, Ind (Macauley) - 0.0137.
Based on the Assembly 2007 voting transfer patterns, it is clear that the elimination of Macauley and the Greens would be insufficient to take another candidate over the quota and only make minor changes to the votes of each surviving candidate. The next to be eliminated would be UCUNF which, regardless of the nature of the transfers, would not lift the TUV vote over that of SF, thus seeing the TUV eliminated next, presumably followed by SF as the combined TUV-UCUNF vote would not be sufficient to allow the DUP to achieve a second quota (and assuming that UCUNF transfer first to Hermon). It would be assumed that the next elimination, SF, would elect the SDLP. Their vote (minus the quota) would be the lowest ensuring they would be eliminated next. At this point the remaining parties would be (in order) Alliance, Independent (Hermon), DUP.

The distribution of the SDLP vote would, in turn, be sufficient to see the Alliance complete an electoral quota. The final seat would be between Hermon (Ind) and the DUP. Based on the pattern of transfers in the Assembly from the SDLP and Alliance to the UUP, relative to the DUP, it would seem more likely that Hermon would take the last seat.

Greater Belfast result: DUP - 1, SF - 1, UCUNF - 1, SDLP - 1, Alliance - 1, Ind - 1.

Second, the 'Northern' constituency. Based on the combined votes of the various parties in the six constituencies, with a quota for election set in the standard fashion, the first count would see the number of quotas received by each party as: SF - 2.0469, DUP - 1.9854, SDLP - 1.2232, UCUNF - 0.9095, TUV - 0.4536, Alliance - 0.2547, People Before Profit - 0.0918, and, Independents - 0.0348. For the purposes of transfers, all independents and People Before Profit were distributed equally between all remaining parties, although the overall numbers are generally negligible.

The first count would see the following seats filled: SF (2), DUP (1), SDLP (1). Having filled four seats, the state of the parties would be DUP - 0.9854, UCUNF - 0.9095, TUV - 0.4536, Alliance - 0.2547, SDLP - 0.2232, People Before Profit - 0.0918, SF - 0.0469, and, Independents - 0.0348.

The remaining two seats would be filled in a relatively straightforward fashion, with the distribution of the remaining SF vote, People Before Profit and Independents sufficient to fill a second DUP quota. Any DUP vote over the second quota would be minimal and see them eliminated with only a minor impact on the vote carried forward by various parties. Whether the next elimination is either the SDLP or Alliance, it would undoubtedly allow UCUNF to achieve a quota and take the remaning seat.

Northern result: SF - 2, DUP - 2, SDLP - 1, UCUNF - 1.

Lastly, the 'Southern' constituency. Based on the combined votes of the various parties in the six constituencies, with a quota for election set in the standard fashion, the first count would see the number of quotas received by each party as: DUP - 1.9339, SF - 1.8665, UCUNF - 1.4335, SDLP - 1.2592, Alliance - 0.2796, TUV - 0.1852, Green - 0.0418, and, Independents - 0.0241.

The first count would see the following seats filled: DUP (1), SF (1), SDLP (1), UCUNF (1). With four seats filled, this would see the proportion of a quota held by each party as DUP - 0.9339, SF - 0.8665, UCUNF - 0.4335, Alliance - 0.2796, SDLP - 0.2592, TUV - 0.1852, Green - 0.0418, and, Independents - 0.0241.

The remaining two seats would be filled in a relatively straightforward fashion, with the distribution of the Independents and Greens insufficient to allow the TUV to avoid elimination. That would be sufficient to see the DUP attain a second quota. The last seat would be similarly straightforward as the transfer of the remaining DUP votes would not see the SDLP pass the Alliance or UCUNF catch SF, thus eliminating the SDLP. Their 0.2592 (+) of a quota would, based on Assembly 2007 transfers, produce enough transfers for SF to reach a second quota and take the last seat.

Southern result: DUP - 2,  SF - 2, UCUNF - 1, SDLP - 1.