Bridgend and Vale of Glamorgan West: New Boundaries 2018 Calculation

Bridgend and Vale of Glamorgan West: Overview

 Projection: LAB seat 

Implied MP at 2017: Madeleine Moon  (LAB)
County/Area: Mid Glamorgan (Wales)
Electorate: 74,094
Turnout: 74.5%

 Implied 2017 VotesImplied 2017 Share
LAB26,29547.6%
CON23,68042.9%
Plaid1,9963.6%
LIB1,2682.3%
UKIP9891.8%
OTH7631.4%
Green2280.4%
LAB Majority2,6154.7%

See overview of other seats in Wales.

Bridgend and Vale of Glamorgan West : Political and Demographic indicators

The table below shows some political and demographic numerical indicators for the new Bridgend and Vale of Glamorgan West constituency, the 'Wales' area and nation.

The political measures include the Left/Right and International/National axes (what does this mean).

The demographic measures are from the 2011 Census and include categories relating to national identity, economic activity, health and education. These categories are those which have the most relevance to political attitudes.

IndicatorSeatWalesAll GB
Party WinnerLABLABCON
Economic Position4° Left10° Left
National Position1° Int3° Int1° Int
EU Leave %52%53%52%
British Identity24%26%29%
Good Health50%47%48%
UK Born93%95%88%
Good Education40%36%39%
Good Job63%46%51%
High SEC64%46%51%
Average Age51.149.648.5
ABC1 Class66%47%53%

Bridgend and Vale of Glamorgan West ranks #330 for "Leave", #411 for "Right" and #396 for "National" out of 600 new seats.

Indicators: Legend and Descriptions

Indicators : Legend and Descriptions

The colour scheme used in the table above is explained in the legend table below. The eight census indicators (British Identity, Good Health, UK Born, Good Education, Good Job, High SEC, Average Age and AB1 Class) all use the same 'Census' colour scheme indicating whether the area's level is above or below the national average.

TopicCat 1Cat 2Cat 3Cat 4Cat 5
Economic PositionVery LeftLeftCentristRightVery Right
National PositionVery IntInternationalCentristNationalVery Nat
EU Leave %Very RemainRemainBalancedLeaveVery Leave
CensusVery LowLowMediumHighVery High

Indicator definitions are given in terms of political data definitions or census categories:

IndicatorCensus
Question
Definition / Included Census Categories
Party WinnerArea party winner : actual election result or projected by Electoral Calculus
Economic PositionEconomic position between 100° Left and 100° Right, estimated by Electoral Calculus from political and demographic data.
National PositionNational position between 100° International and 100° National, estimated by Electoral Calculus from political and demographic data.
EU Leave %EU Referendum vote share for 'Leave' : actual result or estimate
British IdentityNational Identity (KS202)Those answering British, British-Other, or Scottish-British
Good HealthHealth (KS301)Those answering 'Very Good Health'
UK BornCountry of Birth (QS203)Those answering England, Northern Ireland, Scotland, Wales, GB Other, or UK Other
Good EducationHighest level of Qualification (QS501)Level 3 (A-level equivalent) or Level 4+ (degree equivalent)
Good JobOccupation (QS606)Occupation codes 1xx to 4xx (Managers, Professionals, Associates, and office workers)
High SECNS-SeC of Household Reference Person (QS609)National Statistics Socio-economic Classification from 1 to 4 (higher managers and professionals, lower managers and professionals, intermediate occupations, small employers and self-employed).
Average AgeAge (QS103)Average age of adults (18 years and above)
ABC1 ClassApproximated Social Grade (QS611)Approximated social grades A, B and C1

Bridgend and Vale of Glamorgan 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 Bridgend and Vale of Glamorgan 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 Bridgend and Vale of Glamorgan West

The old seat(s) needed are:

Old seat: Bridgend

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

Old seat: BridgendTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
Plaid
Votes
MIN
Votes
OTH
Votes
Total
Votes
BridgendBrackla9,050Bridgend and Vale of Glamorgan West2,0373,5831552604320626,295
BridgendBryntirion, Laleston and Merthyrmawr6,879Bridgend and Vale of Glamorgan West2,2992,125218640400394,785
BridgendCefn Glas1,093Bridgend and Vale of Glamorgan West243437253301507760
BridgendCoity1,625Bridgend and Vale of Glamorgan West67127512840530351,130
BridgendCornelly5,491Bridgend and Vale of Glamorgan West1,3732,1041109012101123,820
BridgendCoychurch Lower1,074Bridgend and Vale of Glamorgan West41028512105026748
BridgendLitchard1,673Bridgend and Vale of Glamorgan West501610325050101,163
BridgendLlangewydd and Brynhyfryd2,094Bridgend and Vale of Glamorgan West36491376170680181,456
BridgendMorfa3,638Bridgend and Vale of Glamorgan West7091,358374003370492,530
BridgendNewcastle4,167Bridgend and Vale of Glamorgan West1,0861,72517270220232,900
BridgendNewton2,814Bridgend and Vale of Glamorgan West9587932901810141,957
BridgendNottage2,629Bridgend and Vale of Glamorgan West898745101500200151,829
BridgendOldcastle3,750Bridgend and Vale of Glamorgan West1,0841,313412201100392,609
BridgendPen-y-fai1,889Bridgend and Vale of Glamorgan West6725717170190281,314
BridgendPendre1,518Bridgend and Vale of Glamorgan West32155645200110051,057
BridgendPorthcawl East Central2,636Bridgend and Vale of Glamorgan West72686745501270551,834
BridgendPorthcawl West Central2,686Bridgend and Vale of Glamorgan West1,03368538390190541,868
BridgendPyle5,776Bridgend and Vale of Glamorgan West1,0022,709411240940494,019
BridgendRest Bay1,702Bridgend and Vale of Glamorgan West826258662006081,184
 Total62,184 17,21321,91291978201,784064843,258

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

Old seat: Ogmore

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

Old seat: OgmoreTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
Plaid
Votes
MIN
Votes
OTH
Votes
Total
Votes
BridgendAberkenfig1,538Ogmore and Aberavon39344813430113001,010
BridgendBettws (Ogmore)1,689Ogmore and Aberavon248769127063001,108
BridgendBlackmill1,882Ogmore and Aberavon1949292044047001,234
BridgendBlaengarw1,357Ogmore and Aberavon10173501104400891
BridgendBryncethin1,012Ogmore and Aberavon189389431203100664
BridgendBryncoch1,703Ogmore and Aberavon2897047135020001,119
BridgendCaerau5,308Ogmore and Aberavon8652,222361990162003,484
BridgendCefn Cribwr1,126Bridgend and Vale of Glamorgan West14055601502800739
BridgendFelindre2,105Ogmore and Aberavon39782410737017001,382
BridgendHendre3,134Ogmore and Aberavon9031,0211779038002,058
BridgendLlangeinor943Ogmore and Aberavon724937704000619
BridgendLlangynwyd2,312Ogmore and Aberavon3278050540332001,518
BridgendMaesteg East3,622Ogmore and Aberavon3731,6527950252002,379
BridgendMaesteg West4,402Ogmore and Aberavon5771,83649820345002,889
BridgendNant-y-moel1,776Ogmore and Aberavon3976362257053001,165
BridgendOgmore Vale2,367Ogmore and Aberavon5678143692045001,554
BridgendPenprysg2,383Ogmore and Aberavon6088331487022001,564
BridgendPontycymmer1,896Ogmore and Aberavon1949481020072001,244
BridgendSarn1,854Ogmore and Aberavon250889032045001,216
BridgendYnysawdre2,561Ogmore and Aberavon39598210350260001,682
Rhondda Cynon TafBrynna2,901Ogmore and Aberavon4291,22726310191001,904
Rhondda Cynon TafGilfach Goch2,625Ogmore and Aberavon2871,2646840063001,722
Rhondda Cynon TafLlanharan2,632Ogmore and Aberavon50492727420228001,728
Rhondda Cynon TafLlanharry2,813Rhondda and Llantrisant4201,1521320242001,847
Rhondda Cynon TafPont-y-clun707 22916452504100464
Rhondda Cynon TafTalbot Green12 430101009
 Total56,660 9,35223,2225901,23402,7950037,193

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

Old seat: Vale of Glamorgan

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

Old seat: Vale of GlamorganTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
Plaid
Votes
MIN
Votes
OTH
Votes
Total
Votes
Vale of GlamorganBaruc4,852Vale of Glamorgan East1,7081,3816870292450233,524
Vale of GlamorganButtrills4,930Vale of Glamorgan East1,0532,0755169272940133,582
Vale of GlamorganCadoc7,581Vale of Glamorgan East1,9653,0684675233080215,506
Vale of GlamorganCastleland3,637Vale of Glamorgan East7191,605326319202032,643
Vale of GlamorganCourt3,636Vale of Glamorgan East7961,542446571660212,641
Vale of GlamorganCowbridge4,685Vale of Glamorgan East2,2279961038460053,403
Vale of GlamorganDinas Powys5,937Vale of Glamorgan East2,3361,40714051313370104,312
Vale of GlamorganDyfan3,879Vale of Glamorgan East1,1911,42412573124062,817
Vale of GlamorganGibbonsdown4,379Vale of Glamorgan East9301,9454288171370223,181
Vale of GlamorganIlltyd6,094Vale of Glamorgan East2,0822,0386752201400274,426
Vale of GlamorganLlandow / Ewenny2,018Bridgend and Vale of Glamorgan West956417247553031,465
Vale of GlamorganLlantwit Major8,011Bridgend and Vale of Glamorgan West3,1881,96927317760520995,818
Vale of GlamorganPeterston-super-Ely1,702Vale of Glamorgan East832345180436011,236
Vale of GlamorganRhoose5,250Vale of Glamorgan East2,3551,24144787540353,814
Vale of GlamorganSt Athan3,407Bridgend and Vale of Glamorgan West1,3621,003236171082,474
Vale of GlamorganSt Bride's Major2,018Bridgend and Vale of Glamorgan West8214382921628051,465
Vale of GlamorganWenvoe1,943Vale of Glamorgan East9814155008021,411
 Total73,959 25,50223,3091,0218684192,295030453,718

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

New seat: Bridgend and Vale of Glamorgan West

The new seat of Bridgend and Vale of Glamorgan West is made up of the following wards, with the transfer-adjusted votes shown.

New seat: Bridgend and Vale of Glamorgan West
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
Plaid
Votes
MIN
Votes
OTH
Votes
Total
Votes
BridgendBrackla8,577Bridgend2,0373,5831552604320626,295
BridgendBryntirion, Laleston and Merthyrmawr6,519Bridgend2,2992,125218640400394,785
BridgendCefn Cribwr1,088Ogmore14055601502800739
BridgendCefn Glas1,036Bridgend243437253301507760
BridgendCoity1,540Bridgend67127512840530351,130
BridgendCornelly5,204Bridgend1,3732,1041109012101123,820
BridgendCoychurch Lower1,018Bridgend41028512105026748
BridgendLitchard1,586Bridgend501610325050101,163
BridgendLlangewydd and Brynhyfryd1,984Bridgend36491376170680181,456
BridgendMorfa3,448Bridgend7091,358374003370492,530
BridgendNewcastle3,949Bridgend1,0861,72517270220232,900
BridgendNewton2,667Bridgend9587932901810141,957
BridgendNottage2,492Bridgend898745101500200151,829
BridgendOldcastle3,554Bridgend1,0841,313412201100392,609
BridgendPen-y-fai1,790Bridgend6725717170190281,314
BridgendPendre1,439Bridgend32155645200110051,057
BridgendPorthcawl East Central2,498Bridgend72686745501270551,834
BridgendPorthcawl West Central2,546Bridgend1,03368538390190541,868
BridgendPyle5,474Bridgend1,0022,709411240940494,019
BridgendRest Bay1,613Bridgend826258662006081,184
Vale of GlamorganLlandow / Ewenny2,061Vale of Glamorgan956417247553031,465
Vale of GlamorganLlantwit Major7,502Vale of Glamorgan3,1881,96927317760520995,818
Vale of GlamorganSt Athan2,412Vale of Glamorgan1,3621,003236171082,474
Vale of GlamorganSt Bride's Major2,097Vale of Glamorgan8214382921628051,465
 Total74,094 23,68026,2951,2689892281,996076355,219

And these are the implied results for 2017 for the new seat of Bridgend and Vale of Glamorgan West.


© 2017 Martin Baxter
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