Vale of Glamorgan East: New Boundaries 2018 Calculation

Vale of Glamorgan East: Overview

Projection: LAB seat

Implied MP at 2017:Unknown (changed seat)  (LAB)
County/Area:South Glamorgan (Wales)
Electorate:78,815
Turnout:71.0%

PartyImplied 2017 VotesImplied 2017 Share
LAB25,66045.8%
CON24,93044.5%
Plaid2,4894.4%
LIB1,1952.1%
UKIP9721.7%
Green4530.8%
OTH2680.5%
LAB Majority7301.3%

See overview of other seats in Wales.



Introduction

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Vale of Glamorgan East 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.

Vale of Glamorgan East: Map

Boundary Lines courtesy of Ordnance Survey OpenData © Crown copyright 2015, Map © OpenStreetMap contributors

List of old seats forming part of Vale of Glamorgan East

The old seat(s) needed are:

Old seat: Cardiff South and Penarth

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

Old seat: Cardiff South and PenarthTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
Plaid
Votes
MIN
Votes
OTH
Votes
Total
Votes
CardiffButetown6,524Cardiff South and East1,3962,63318112281362084,783
CardiffGrangetown11,671Cardiff West2,3655,5153221361386220519,149
CardiffLlanrumney7,387Cardiff South and East1,1503,6731029433167055,224
CardiffPontprennau / Old St Mellons117Cardiff North343821120078
CardiffRumney6,304Cardiff South and East1,3872,483667426850154,136
CardiffSplott8,454Cardiff South and East1,4134,267204107561930256,265
CardiffTrowbridge10,585Cardiff South and East1,9715,05621613376173067,631
Vale of GlamorganCornerswell3,885Vale of Glamorgan East8441,402724419108052,494
Vale of GlamorganLlandough1,454Vale of Glamorgan East339509151664304932
Vale of GlamorganPlymouth4,419Vale of Glamorgan East1,5021,011814018980142,764
Vale of GlamorganSt Augustine's4,913Vale of Glamorgan East1,2441,4678944521700163,082
Vale of GlamorganStanwell3,178Vale of Glamorgan East6961,23147291477052,099
Vale of GlamorganSully3,531Vale of Glamorgan East9798983310112610162,100
 Total72,422 15,32030,1831,4309415322,161017050,737

The full details of these calculations are given on the Cardiff South and Penarth 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 GlamorganBaruc4,636Vale of Glamorgan East1,6711,3759977382390253,524
Vale of GlamorganButtrills4,175Vale of Glamorgan East1,2321,9599264341820193,582
Vale of GlamorganCadoc6,842Vale of Glamorgan East1,8913,06111497382780285,507
Vale of GlamorganCastleland3,096Vale of Glamorgan East8221,555654427124062,643
Vale of GlamorganCourt3,031Vale of Glamorgan East8481,5316150251110142,640
Vale of GlamorganCowbridge4,997Vale of Glamorgan East2,2069364639211310233,402
Vale of GlamorganDinas Powys6,139Vale of Glamorgan East2,4331,39910379362490124,311
Vale of GlamorganDyfan3,983Vale of Glamorgan East1,1981,376534422118072,818
Vale of GlamorganGibbonsdown3,646Vale of Glamorgan East9781,9624948241030163,180
Vale of GlamorganIlltyd5,951Vale of Glamorgan East1,9232,00810781372410294,426
Vale of GlamorganLlandow / Ewenny2,061Bridgend and Vale of Glamorgan West9603821819876031,466
Vale of GlamorganLlantwit Major7,502Bridgend and Vale of Glamorgan West2,9902,358110107451600485,818
Vale of GlamorganPeterston-super-Ely1,828Vale of Glamorgan East867320710423051,236
Vale of GlamorganRhoose5,158Vale of Glamorgan East2,2851,2805052201060223,815
Vale of GlamorganSt Athan2,412Bridgend and Vale of Glamorgan West1,318968183211920362,475
Vale of GlamorganSt Bride's Major2,097Bridgend and Vale of Glamorgan West90546314152536081,466
Vale of GlamorganWenvoe2,122Vale of Glamorgan East9723801213627021,412
 Total69,676 25,49923,3131,0188714212,296030353,721

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

New seat: Vale of Glamorgan East

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

New seat: Vale of Glamorgan East
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
Plaid
Votes
MIN
Votes
OTH
Votes
Total
Votes
Vale of GlamorganBaruc4,852Vale of Glamorgan1,6711,3759977382390253,524
Vale of GlamorganButtrills4,930Vale of Glamorgan1,2321,9599264341820193,582
Vale of GlamorganCadoc7,581Vale of Glamorgan1,8913,06111497382780285,507
Vale of GlamorganCastleland3,637Vale of Glamorgan8221,555654427124062,643
Vale of GlamorganCornerswell3,760Cardiff South and Penarth8441,402724419108052,494
Vale of GlamorganCourt3,636Vale of Glamorgan8481,5316150251110142,640
Vale of GlamorganCowbridge4,685Vale of Glamorgan2,2069364639211310233,402
Vale of GlamorganDinas Powys5,937Vale of Glamorgan2,4331,39910379362490124,311
Vale of GlamorganDyfan3,879Vale of Glamorgan1,1981,376534422118072,818
Vale of GlamorganGibbonsdown4,379Vale of Glamorgan9781,9624948241030163,180
Vale of GlamorganIlltyd6,094Vale of Glamorgan1,9232,00810781372410294,426
Vale of GlamorganLlandough1,405Cardiff South and Penarth339509151664304932
Vale of GlamorganPeterston-super-Ely1,702Vale of Glamorgan867320710423051,236
Vale of GlamorganPlymouth4,166Cardiff South and Penarth1,5021,011814018980142,764
Vale of GlamorganRhoose5,250Vale of Glamorgan2,2851,2805052201060223,815
Vale of GlamorganSt Augustine's4,645Cardiff South and Penarth1,2441,4678944521700163,082
Vale of GlamorganStanwell3,167Cardiff South and Penarth6961,23147291477052,099
Vale of GlamorganSully3,167Cardiff South and Penarth9798983310112610162,100
Vale of GlamorganWenvoe1,943Vale of Glamorgan9723801213627021,412
 Total78,815 24,93025,6601,1959724532,489026855,967

And these are the implied results for 2017 for the new seat of Vale of Glamorgan East. Please note that the wards used are those of 2015 in order to be consistent with those used by the Boundary Commissions.


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