Belfast South West: New Boundaries 2018 Calculation

Belfast South West: Overview

 Projection: SF seat 

Implied MP at 2017: Paul Maskey  (SF)
County/Area: Antrim (Northern Ireland)
Electorate: 73,795
Turnout: 68.2%

 Implied 2017 VotesImplied 2017 Share
SF24,39848.5%
DUP8,06516.0%
SDLP7,58315.1%
MIN7,20214.3%
Green1,6983.4%
OTH7461.5%
UUP6231.2%
SF Majority16,33332.5%

See overview of other seats in Northern Ireland.

Belfast South West: Map

Boundary Lines courtesy of Ordnance Survey OpenData © Crown copyright 2015

Introduction

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Belfast South West been in force at that time. The basic idea of the calculation is to look at the district council wards which make up the new seat, and estimate how they voted in 2017. This estimate is based on the recent local election results in those wards, with adjustments made to allow for different turnouts and different voting patterns for local and general elections.

In many cases, wards are divided between several old constituencies or between new constituencies. So the same ward may be shown more than once, but the electorate shown will reflect that ward sub-section.

Election results from a recent local election are given. This is usually the local election closest to 2015 from the period 2012-2015. For multiple-member wards, the votes shown are the sum of the votes cast for all candidates of each party. A negative number indicates candidate(s) elected unopposed.

Calculation method

There are two problems with using the raw (actual) local election results to imply general election results ward-by-ward. Firstly, turnout can be different between local and general elections, which means that the total number of local votes cast does not equal the number of votes cast in each old seat at the general election. To correct for this, we adjust the local votes to match the general election turnout. Each ward's result is scaled, whilst keeping constant the percentage support for each party, so that the total turnout adds up to the old seat's general election turnout. All wards in the old seat are assumed to have the same percentage turnout.

Secondly, even though we now have the correct number of votes in the old seat, the party totals will not match the general election result. Some parties do better at the local election than the general election, and others do vice versa. We call these strong and weak parties respectively. The next step is to transfer votes from strong parties to weak parties. This is done by taking votes proportionally away from strong parties and putting them in a transfer pool. For instance if a party got 12,500 local votes, but only 10,000 general election votes, it will lose 20% over all the wards. These votes in each ward will be put in the ward's transfer pool and allocated to the weak parties. Weak parties will get votes transferred to them in proportion to the votes they need over the old seat. For instance, if two weak parties need 4,000 and 1,000 votes respectively, the first party will get 80% of each ward's transfer pool and the second party will get 20% of each ward's transfer pool. The transfer of votes between parties is done using the Electoral Calculus Transition Model.

More details of the calculation formulas are available.

List of old seats forming part of Belfast South West

The old seat(s) needed are:

Old seat: Belfast South

The table shows the transfer-adjusted results for each ward in the old seat of Belfast South, as well as showing which new seat each ward is in.

Old seat: Belfast SouthTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatUUP
Votes
SDLP
Votes
DUP
Votes
UKIP
Votes
Green
Votes
SF
Votes
MIN
Votes
OTH
Votes
Total
Votes
BelfastBelvoir2,735Belfast East5550261106526230691,810
BelfastBlackstaff4,153Belfast South West725827720270342688212,747
BelfastCentral6,647Belfast South West1149321,23604315471,101344,395
BelfastCregagh1,365Belfast East5328822901331270902
BelfastFinaghy2,684Belfast South West5349260106425730091,776
BelfastHillfoot1,642Belfast East64346276015376901,086
BelfastMalone2,779Belfast South West55509621067266310101,838
BelfastMerok0Belfast East000000000
BelfastMusgrave2,997Belfast South West60548670071286334101,979
BelfastOrmeau3,872Belfast East675427180251318641202,557
BelfastRavenhill2,862Belfast East1126024810266541601,891
BelfastRosetta3,352Belfast East1317075620317671812,217
BelfastStranmillis4,849Belfast South West836819020313399803253,206
BelfastUpper Malone2,801Belfast South West56513627067268312101,853
BelfastWindsor6,402Belfast South West1108971,19004155271,060334,232
BelfastWoodstock3,611Belfast East1417606060338262012,387
Lisburn and CastlereaghBeechill2,210Down West50397530018122334101,461
Lisburn and CastlereaghCairnshill1,868Strangford4233644801510328391,236
Lisburn and CastlereaghCarryduff East1,737Strangford393134170149626381,150
Lisburn and CastlereaghCarryduff West2,049Down West46368490017113310101,354
Lisburn and CastlereaghGalwally1,912Strangford4334345901610628991,265
Lisburn and CastlereaghKnockbracken1,904Down West4334245601610628891,260
Lisburn and CastlereaghNewtownbreda1,675Down West383024010149225381,108
 Total66,106 1,52711,30213,30302,2427,1457,94524643,710

The full details of these calculations are given on the Belfast South seat details page. Click on "Show workings".

Old seat: Belfast West

The table shows the transfer-adjusted results for each ward in the old seat of Belfast West, as well as showing which new seat each ward is in.

Old seat: Belfast WestTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatUUP
Votes
SDLP
Votes
DUP
Votes
UKIP
Votes
Green
Votes
SF
Votes
MIN
Votes
OTH
Votes
Total
Votes
BelfastAndersonstown3,137Belfast South West014188001,557203532,042
BelfastBallygomartin3,887Belfast North West085976009713951032,530
BelfastBallymurphy3,386Belfast South West015295001,680220572,204
BelfastBeechmount3,815Belfast North West0172107001,893248652,485
BelfastCentral177Belfast South West013310046195114
BelfastClonard3,807Belfast North West084956009513871012,479
BelfastCollin Glen3,849Belfast South West0173108001,910249652,505
BelfastDunmurry2,813Belfast South West017993001,411117311,831
BelfastFalls3,431Belfast North West07686200856348912,233
BelfastFalls Park3,153Belfast South West014288001,564204532,051
BelfastForth River2,435Belfast North West05461200608247651,586
BelfastLadybrook3,384Belfast South West0216111001,698141372,203
BelfastLagmore5,089Belfast South West0325167002,553212553,312
BelfastPoleglass4,163Belfast South West0265137002,089174452,710
BelfastShankill2,144Belfast North West04753800535217571,394
BelfastShaw's Road3,416Belfast South West015496001,695221582,224
BelfastStewartstown3,451Belfast South West0220113001,730144382,245
BelfastTurf Lodge3,351Belfast South West015094001,662218572,181
BelfastTwinbrook3,232Belfast South West0206106001,621135352,103
BelfastWoodvale306Belfast North West07770077318200
 Total62,426 02,8615,4550027,1074,1301,07940,632

The full details of these calculations are given on the Belfast West seat details page. Click on "Show workings".

Old seat: Lagan Valley

The table shows the transfer-adjusted results for each ward in the old seat of Lagan Valley, as well as showing which new seat each ward is in.

Old seat: Lagan ValleyTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatUUP
Votes
SDLP
Votes
DUP
Votes
UKIP
Votes
Green
Votes
SF
Votes
MIN
Votes
OTH
Votes
Total
Votes
Armagh, Banbridge and CraigavonDonaghcloney75Down West133260025150
Armagh, Banbridge and CraigavonDromore3,215Down West5311061,0910050192261,996
Armagh, Banbridge and CraigavonGransha2,493Down West412828460038149201,547
Armagh, Banbridge and CraigavonQuilly2,989Down West495981,0130046178241,854
BelfastBelvoir265Belfast East1442640021193163
BelfastDunmurry908Belfast South West209311900290375564
Lisburn and CastlereaghBallinderry2,566Antrim South2471918850016097131,593
Lisburn and CastlereaghBallymacash2,231Antrim South165115935000149201,384
Lisburn and CastlereaghBallymacbrennan2,064Down West21126843000178241,282
Lisburn and CastlereaghBallymacoss3,065Antrim South2261581,284000205281,901
Lisburn and CastlereaghBlaris2,177Down West31586760000168231,352
Lisburn and CastlereaghDerryaghy2,844Antrim South2321631,01500100223311,764
Lisburn and CastlereaghDromara2,386Down West24430973000205281,480
Lisburn and CastlereaghDrumbo2,077Down West21326848000178241,289
Lisburn and CastlereaghHarmony Hill2,205Antrim South1811277860077173241,368
Lisburn and CastlereaghHilden2,634Antrim South2151529400092207281,634
Lisburn and CastlereaghHillhall2,553Down West261321,041000220301,584
Lisburn and CastlereaghHillsborough2,234Down West32289779000172241,386
Lisburn and CastlereaghKnockmore2,735Antrim South2031411,146000183251,698
Lisburn and CastlereaghLagan2,172Down West31486758000168231,349
Lisburn and CastlereaghLagan Valley2,436Antrim South1801251,021000163221,511
Lisburn and CastlereaghLambeg2,416Antrim South1981398630085190261,501
Lisburn and CastlereaghLisnagarvey2,219Antrim South165114929000149201,377
Lisburn and CastlereaghMaghaberry2,914Antrim South2792171,00500183110151,809
Lisburn and CastlereaghMagheralave2,275Antrim South1851318130081178241,412
Lisburn and CastlereaghMaze2,064Down West29981721000160221,283
Lisburn and CastlereaghMoira2,679Down West387106935000207281,663
Lisburn and CastlereaghOld Warren2,865Antrim South2121481,202000192261,780
Lisburn and CastlereaghRavernet2,103Down West21527858000181251,306
Lisburn and CastlereaghStonyford344Antrim South33261180021132213
Lisburn and CastlereaghWallace Park2,847Antrim South2321631,01700100223311,766
Lisburn and CastlereaghWhite Mountain3,198Antrim South3062381,10200200121171,984
Newry, Mourne and DownBallyward132Down South8222700214183
 Total72,380 7,5333,38326,763001,5674,99768344,926

The full details of these calculations are given on the Lagan Valley seat details page. Click on "Show workings".

New seat: Belfast South West

The new seat of Belfast South West is made up of the following wards, with the transfer-adjusted votes shown.

New seat: Belfast South West
DistrictWardElectorate
2017
Old Seat UUP
Votes
SDLP
Votes
DUP
Votes
UKIP
Votes
Green
Votes
SF
Votes
MIN
Votes
OTH
Votes
Total
Votes
BelfastAndersonstown3,643Belfast West014188001,557203532,042
BelfastBallymurphy3,379Belfast West015295001,680220572,204
BelfastBlackstaff3,700Belfast South725827720270342688212,747
BelfastCentral115Belfast West3253301116301119
BelfastCentral4,247Belfast South1119201,23404205771,090384,390
BelfastCollin Glen3,890Belfast West0173108001,910249652,505
BelfastDunmurry2,870Belfast West15207162001,297117271,825
BelfastDunmurry894Lagan Valley5655000404379570
BelfastFalls Park3,648Belfast West014288001,564204532,051
BelfastFinaghy3,422Belfast South5349260106425730091,776
BelfastLadybrook3,634Belfast West0216111001,698141372,203
BelfastLagmore4,411Belfast West0325167002,553212553,312
BelfastMalone3,415Belfast South55509621067266310101,838
BelfastMusgrave3,489Belfast South60548670071286334101,979
BelfastPoleglass3,679Belfast West0265137002,089174452,710
BelfastShaw's Road3,818Belfast West015496001,695221582,224
BelfastStewartstown3,568Belfast West0220113001,730144382,245
BelfastStranmillis3,850Belfast South836819020313399803253,206
BelfastTurf Lodge3,474Belfast West015094001,662218572,181
BelfastTwinbrook3,340Belfast West0206106001,621135352,103
BelfastUpper Malone3,487Belfast South56513627067268312101,853
BelfastWindsor3,822Belfast South1108971,19004155271,060334,232
 Total73,795 6237,5838,06501,69824,3987,20274650,315

And these are the implied results for 2017 for the new seat of Belfast South West.


© 2017 Martin Baxter
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