Cynon Valley and Pontypridd: New Boundaries 2018 Calculation

Cynon Valley and Pontypridd: Overview

 Projection: LAB seat 

Implied MP at 2017: Ann Clwyd  (LAB)
County/Area: Mid Glamorgan (Wales)
Electorate: 78,005
Turnout: 67.6%

 Implied 2017 VotesImplied 2017 Share
LAB30,92758.7%
CON11,56922.0%
Plaid6,35312.1%
LIB2,0653.9%
UKIP1,7853.4%
LAB Majority19,35836.7%

See overview of other seats in Wales.

Cynon Valley and Pontypridd : Political and Demographic indicators

The table below shows some political and demographic numerical indicators for the new Cynon Valley and Pontypridd 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 Position17° Left10° Left
National Position4° Int3° Int1° Int
EU Leave %54%53%52%
British Identity29%26%29%
Good Health49%47%48%
UK Born93%95%88%
Good Education46%36%39%
Good Job56%46%51%
High SEC58%46%51%
Average Age53.049.648.5
ABC1 Class60%47%53%

Cynon Valley and Pontypridd ranks #290 for "Leave", #560 for "Right" and #432 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

Cynon Valley and Pontypridd: 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 Cynon Valley and Pontypridd 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 Cynon Valley and Pontypridd

The old seat(s) needed are:

Old seat: Cynon Valley

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

Old seat: Cynon ValleyTransfer-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 TafAberaman North3,956Cynon Valley and Pontypridd2981,78420610288002,451
Rhondda Cynon TafAberaman South3,454Cynon Valley and Pontypridd3421,4293750290002,139
Rhondda Cynon TafAbercynon4,757Cynon Valley and Pontypridd6781,744691810275002,947
Rhondda Cynon TafAberdare East4,767Cynon Valley and Pontypridd5012,03745680303002,954
Rhondda Cynon TafAberdare West / Llwydcoed6,938Cynon Valley and Pontypridd1,0302,282451610780004,298
Rhondda Cynon TafCilfynydd2,100Cynon Valley and Pontypridd36163796730134001,301
Rhondda Cynon TafCwmbach3,281Cynon Valley and Pontypridd4191,2314560323002,033
Rhondda Cynon TafGlyncoch2,129Cynon Valley and Pontypridd1091,108717078001,319
Rhondda Cynon TafHirwaun3,114Cynon Valley and Pontypridd4139983720443001,929
Rhondda Cynon TafMountain Ash East2,169Cynon Valley and Pontypridd34859228880288001,344
Rhondda Cynon TafMountain Ash West3,366Cynon Valley and Pontypridd3111,37411980291002,085
Rhondda Cynon TafPen-y-waun2,286Cynon Valley and Pontypridd3148761620163001,416
Rhondda Cynon TafPenrhiwceiber4,273Cynon Valley and Pontypridd3561,860121060313002,647
Rhondda Cynon TafRhigos1,267Cynon Valley and Pontypridd209418031012800786
Rhondda Cynon TafYnysybwl3,475Cynon Valley and Pontypridd4771,0352411210279002,153
 Total51,332 6,16619,4055851,27004,3760031,802

The full details of these calculations are given on the Cynon Valley 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 Llantrisant4561,35156430163002,069
Rhondda Cynon TafChurch Village3,794Cynon Valley and Pontypridd6541,50456300255002,499
Rhondda Cynon TafGraig (Pontypridd)1,855Cynon Valley and Pontypridd24677953180127001,223
Rhondda Cynon TafHawthorn2,699Cynon Valley and Pontypridd297946112630359001,777
Rhondda Cynon TafLlanharry94 104111090062
Rhondda Cynon TafLlantrisant Town3,665Rhondda and Llantrisant6171,46082260228002,413
Rhondda Cynon TafLlantwit Fardre4,602Cynon Valley and Pontypridd1,4091,24980600234003,032
Rhondda Cynon TafPont-y-clun5,297Rhondda and Llantrisant1,5451,340971710336003,489
Rhondda Cynon TafPontypridd Town2,132Cynon Valley and Pontypridd420681138600104001,403
Rhondda Cynon TafRhondda3,510Cynon Valley and Pontypridd6141,317491090223002,312
Rhondda Cynon TafRhydfelen Central / Ilan3,370Cynon Valley and Pontypridd2121,61383480264002,220
Rhondda Cynon TafTaffs Well2,788Cardiff West3711,05751280330001,837
Rhondda Cynon TafTalbot Green1,972Rhondda and Llantrisant5426024645064001,299
Rhondda Cynon TafTon-teg3,022Cynon Valley and Pontypridd6561,010159620104001,991
Rhondda Cynon TafTonyrefail East4,460Rhondda and Llantrisant8021,622891000324002,937
Rhondda Cynon TafTonyrefail West4,800Rhondda and Llantrisant6911,846361020486003,161
Rhondda Cynon TafTrallwng2,841Cynon Valley and Pontypridd424871423330120001,871
Rhondda Cynon TafTreforest3,900Cynon Valley and Pontypridd4711,552327320187002,569
Rhondda Cynon TafTyn-y-nant2,626Rhondda and Llantrisant2171,26126410185001,730
 Total60,567 10,65422,1021,9641,07204,1020039,894

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

New seat: Cynon Valley and Pontypridd

The new seat of Cynon Valley and Pontypridd is made up of the following wards, with the transfer-adjusted votes shown.

New seat: Cynon Valley and Pontypridd
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
Plaid
Votes
MIN
Votes
OTH
Votes
Total
Votes
Rhondda Cynon TafAberaman North3,807Cynon Valley2981,78420610288002,451
Rhondda Cynon TafAberaman South3,324Cynon Valley3421,4293750290002,139
Rhondda Cynon TafAbercynon4,578Cynon Valley6781,744691810275002,947
Rhondda Cynon TafAberdare East4,588Cynon Valley5012,03745680303002,954
Rhondda Cynon TafAberdare West / Llwydcoed6,678Cynon Valley1,0302,282451610780004,298
Rhondda Cynon TafChurch Village3,469Pontypridd6541,50456300255002,499
Rhondda Cynon TafCilfynydd2,021Cynon Valley36163796730134001,301
Rhondda Cynon TafCwmbach3,158Cynon Valley4191,2314560323002,033
Rhondda Cynon TafGlyncoch2,049Cynon Valley1091,108717078001,319
Rhondda Cynon TafGraig (Pontypridd)1,455Pontypridd24677953180127001,223
Rhondda Cynon TafHawthorn2,869Pontypridd297946112630359001,777
Rhondda Cynon TafHirwaun2,997Cynon Valley4139983720443001,929
Rhondda Cynon TafLlantwit Fardre4,593Pontypridd1,4091,24980600234003,032
Rhondda Cynon TafMountain Ash East2,088Cynon Valley34859228880288001,344
Rhondda Cynon TafMountain Ash West3,240Cynon Valley3111,37411980291002,085
Rhondda Cynon TafPen-y-waun2,200Cynon Valley3148761620163001,416
Rhondda Cynon TafPenrhiwceiber4,113Cynon Valley3561,860121060313002,647
Rhondda Cynon TafPontypridd Town2,141Pontypridd420681138600104001,403
Rhondda Cynon TafRhigos1,219Cynon Valley209418031012800786
Rhondda Cynon TafRhondda3,364Pontypridd6141,317491090223002,312
Rhondda Cynon TafRhydfelen Central / Ilan2,924Pontypridd2121,61383480264002,220
Rhondda Cynon TafTon-Teg3,170Pontypridd6561,010159620104001,991
Rhondda Cynon TafTrallwng2,770Pontypridd424871423330120001,871
Rhondda Cynon TafTreforest1,845Pontypridd4711,552327320187002,569
Rhondda Cynon TafYnysybwl3,345Cynon Valley4771,0352411210279002,153
 Total78,005 11,56930,9272,0651,78506,3530052,699

And these are the implied results for 2017 for the new seat of Cynon Valley and Pontypridd.


© 2017 Martin Baxter
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