Rhondda and Llantrisant: New Boundaries 2018 Calculation

Rhondda and Llantrisant: Overview

 Projection: LAB seat 

Implied MP at 2017: Chris Bryant  (LAB)
County/Area: Mid Glamorgan (Wales)
Electorate: 80,099
Turnout: 65.4%

 Implied 2017 VotesImplied 2017 Share
LAB31,93160.9%
Plaid9,61418.3%
CON8,45416.1%
UKIP1,4932.8%
LIB9221.8%
LAB Majority22,31742.6%

See overview of other seats in Wales.

Rhondda and Llantrisant : Political and Demographic indicators

The table below shows some political and demographic numerical indicators for the new Rhondda and Llantrisant 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 Position21° Left10° Left
National Position5° Int3° Int1° Int
EU Leave %53%53%52%
British Identity19%26%29%
Good Health44%47%48%
UK Born98%95%88%
Good Education29%36%39%
Good Job43%46%51%
High SEC40%46%51%
Average Age49.349.648.5
ABC1 Class40%47%53%

Rhondda and Llantrisant ranks #307 for "Leave", #591 for "Right" and #440 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

Rhondda and Llantrisant: 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 Rhondda and Llantrisant 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 Rhondda and Llantrisant

The old seat(s) needed are:

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 Aberavon28949417380172001,010
BridgendBettws (Ogmore)1,689Ogmore and Aberavon215815833039001,110
BridgendBlackmill1,882Ogmore and Aberavon2798571236053001,237
BridgendBlaengarw1,357Ogmore and Aberavon187619172904000892
BridgendBryncethin1,012Ogmore and Aberavon162413262004400665
BridgendBryncoch1,703Ogmore and Aberavon2647383434049001,119
BridgendCaerau5,308Ogmore and Aberavon7262,492291210117003,485
BridgendCefn Cribwr1,126Bridgend and Vale of Glamorgan West18648352304200739
BridgendFelindre2,105Ogmore and Aberavon4028225143064001,382
BridgendHendre3,134Ogmore and Aberavon6301,2432164098002,056
BridgendLlangeinor943Ogmore and Aberavon15141841902800620
BridgendLlangynwyd2,312Ogmore and Aberavon44578816540214001,517
BridgendMaesteg East3,622Ogmore and Aberavon5641,50618840206002,378
BridgendMaesteg West4,402Ogmore and Aberavon6841,700901000316002,890
BridgendNant-y-moel1,776Ogmore and Aberavon2977561942053001,167
BridgendOgmore Vale2,367Ogmore and Aberavon3949823654088001,554
BridgendPenprysg2,383Ogmore and Aberavon44394924490100001,565
BridgendPontycymmer1,896Ogmore and Aberavon2568761942052001,245
BridgendSarn1,854Ogmore and Aberavon2708401638054001,218
BridgendYnysawdre2,561Ogmore and Aberavon46093521570209001,682
Rhondda Cynon TafBrynna2,901Ogmore and Aberavon5221,07618610229001,906
Rhondda Cynon TafGilfach Goch2,625Ogmore and Aberavon3661,1964852062001,724
Rhondda Cynon TafLlanharan2,632Ogmore and Aberavon49896615550194001,728
Rhondda Cynon TafLlanharry2,813Rhondda and Llantrisant4951,06924580201001,847
Rhondda Cynon TafPont-y-clun707Rhondda and Llantrisant16719162907100464
Rhondda Cynon TafTalbot Green12Rhondda and Llantrisant240001007
 Total56,660 9,35423,2285941,23502,7960037,207

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

Old seat: Pontypridd

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

Old seat: PontypriddTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
Plaid
Votes
MIN
Votes
OTH
Votes
Total
Votes
Rhondda Cynon TafBeddau3,140Rhondda and Llantrisant4801,28365480192002,068
Rhondda Cynon TafChurch Village3,794Cynon Valley and Pontypridd7111,38387550262002,498
Rhondda Cynon TafGraig (Pontypridd)1,855Cynon Valley and Pontypridd2657775629094001,221
Rhondda Cynon TafHawthorn2,699Cynon Valley and Pontypridd393970124460245001,778
Rhondda Cynon TafLlantrisant Town3,665Rhondda and Llantrisant6651,36571560257002,414
Rhondda Cynon TafLlantwit Fardre4,602Cynon Valley and Pontypridd1,3461,21586700314003,031
Rhondda Cynon TafPontypridd Town2,132Cynon Valley and Pontypridd403698124370142001,404
Rhondda Cynon TafRhondda3,510Cynon Valley and Pontypridd5541,42595600179002,313
Rhondda Cynon TafRhydfelen Central / Ilan3,370Cynon Valley and Pontypridd3851,533102460153002,219
Rhondda Cynon TafTaffs Well2,788Cardiff West4551,00467460266001,838
Rhondda Cynon TafTon-teg3,022Cynon Valley and Pontypridd6241,020164500132001,990
Rhondda Cynon TafTonyrefail East4,460Rhondda and Llantrisant7251,680168800284002,937
Rhondda Cynon TafTonyrefail West4,800Rhondda and Llantrisant7191,851100820408003,160
Rhondda Cynon TafTrallwng2,841Cynon Valley and Pontypridd489960223490151001,872
Rhondda Cynon TafTreforest3,900Cynon Valley and Pontypridd5751,547219570171002,569
Rhondda Cynon TafTyn-y-nant2,626Rhondda and Llantrisant3401,16351380137001,729
Rhondda Cynon TafLlanharry94Rhondda and Llantrisant153721070062
Rhondda Cynon TafPont-y-clun5,297Rhondda and Llantrisant1,1531,4391131860599003,490
Rhondda Cynon TafTalbot Green1,972Rhondda and Llantrisant35975445340108001,300
 Total60,567 10,65622,1041,9621,07004,1010039,893

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

Old seat: Rhondda

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

Old seat: RhonddaTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
Plaid
Votes
MIN
Votes
OTH
Votes
Total
Votes
Rhondda Cynon TafCwm Clydach2,028Rhondda and Llantrisant1249069350248001,322
Rhondda Cynon TafCymmer3,996Rhondda and Llantrisant2411,81516680465002,605
Rhondda Cynon TafFerndale3,034Rhondda and Llantrisant2221,32823590345001,977
Rhondda Cynon TafLlwyn-y-pia1,638Rhondda and Llantrisant9869112280239001,068
Rhondda Cynon TafMaerdy2,295Rhondda and Llantrisant1151,1356380202001,496
Rhondda Cynon TafPentre3,791Rhondda and Llantrisant2981,35420690731002,472
Rhondda Cynon TafPen-y-graig4,033Rhondda and Llantrisant2711,67118660604002,630
Rhondda Cynon TafPorth4,325Rhondda and Llantrisant3201,68230760714002,822
Rhondda Cynon TafTonypandy2,722Rhondda and Llantrisant1921,13917470381001,776
Rhondda Cynon TafTrealaw2,933Rhondda and Llantrisant1951,34215500310001,912
Rhondda Cynon TafTreherbert4,159Rhondda and Llantrisant2381,58513770799002,712
Rhondda Cynon TafTreorchy5,588Rhondda and Llantrisant4352,0392010201,047003,643
Rhondda Cynon TafTylorstown3,301Rhondda and Llantrisant1501,6867490260002,152
Rhondda Cynon TafYnyshir2,411Rhondda and Llantrisant15799616430360001,572
Rhondda Cynon TafYstrad4,259Rhondda and Llantrisant2781,72655740644002,777
 Total50,513 3,33421,09527788107,3490032,936

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

New seat: Rhondda and Llantrisant

The new seat of Rhondda and Llantrisant is made up of the following wards, with the transfer-adjusted votes shown.

New seat: Rhondda and Llantrisant
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
Plaid
Votes
MIN
Votes
OTH
Votes
Total
Votes
Rhondda Cynon TafBeddau3,140Pontypridd4801,28365480192002,068
Rhondda Cynon TafCwm Clydach2,028Rhondda1249069350248001,322
Rhondda Cynon TafCymmer3,996Rhondda2411,81516680465002,605
Rhondda Cynon TafFerndale3,034Rhondda2221,32823590345001,977
Rhondda Cynon TafLlanharry2,813Ogmore4951,06924580201001,847
Rhondda Cynon TafLlanharry94Pontypridd153721070062
Rhondda Cynon TafLlantrisant Town3,665Pontypridd6651,36571560257002,414
Rhondda Cynon TafLlwyn-y-pia1,638Rhondda9869112280239001,068
Rhondda Cynon TafMaerdy2,295Rhondda1151,1356380202001,496
Rhondda Cynon TafPen-y-graig4,033Rhondda2711,67118660604002,630
Rhondda Cynon TafPentre3,791Rhondda2981,35420690731002,472
Rhondda Cynon TafPont-y-clun5,297Pontypridd1,1531,4391131860599003,490
Rhondda Cynon TafPont-y-clun707Ogmore16719162907100464
Rhondda Cynon TafPorth4,325Rhondda3201,68230760714002,822
Rhondda Cynon TafTalbot Green1,972Pontypridd35975445340108001,300
Rhondda Cynon TafTalbot Green12Ogmore240001007
Rhondda Cynon TafTonypandy2,722Rhondda1921,13917470381001,776
Rhondda Cynon TafTonyrefail East4,460Pontypridd7251,680168800284002,937
Rhondda Cynon TafTonyrefail West4,800Pontypridd7191,851100820408003,160
Rhondda Cynon TafTrealaw2,933Rhondda1951,34215500310001,912
Rhondda Cynon TafTreherbert4,159Rhondda2381,58513770799002,712
Rhondda Cynon TafTreorchy5,588Rhondda4352,0392010201,047003,643
Rhondda Cynon TafTylorstown3,301Rhondda1501,6867490260002,152
Rhondda Cynon TafTyn-y-nant2,626Pontypridd3401,16351380137001,729
Rhondda Cynon TafYnyshir2,411Rhondda15799616430360001,572
Rhondda Cynon TafYstrad4,259Rhondda2781,72655740644002,777
 Total80,099 8,45431,9319221,49309,6140052,414

And these are the implied results for 2017 for the new seat of Rhondda and Llantrisant.


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