Carshalton and Wallington: New Boundaries 2018 Calculation

Carshalton and Wallington: Overview

 Projection: CON seat 

Implied MP at 2017: Unknown (changed seat)  (CON)
County/Area: Sutton (London)
Electorate: 75,579
Turnout: 74.5%

 Implied 2017 VotesImplied 2017 Share
CON22,77940.5%
LIB22,04039.2%
LAB10,30018.3%
Green5381.0%
MIN4340.8%
OTH1900.3%
CON Majority7391.3%

See overview of other seats in London.

Carshalton and Wallington : Political and Demographic indicators

The table below shows some political and demographic numerical indicators for the new Carshalton and Wallington constituency, the 'London' 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.

IndicatorSeatLondonAll GB
Party WinnerCONLABCON
Economic Position21° Right11° Right
National Position17° Int29° Int1° Int
EU Leave %56%40%52%
British Identity32%38%29%
Good Health51%50%48%
UK Born83%64%88%
Good Education51%48%39%
Good Job53%61%51%
High SEC45%55%51%
Average Age39.844.148.5
ABC1 Class60%62%53%

Carshalton and Wallington ranks #235 for "Leave", #15 for "Right" and #511 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

Carshalton and Wallington: 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 Carshalton and Wallington 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 Carshalton and Wallington

The old seat(s) needed are:

Old seat: Carshalton and Wallington

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

Old seat: Carshalton and WallingtonTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
SuttonBeddington North7,675Carshalton and Wallington2,1839992,217042038195,498
SuttonBeddington South7,915Carshalton and Wallington2,4291,1212,069012029105,670
SuttonCarshalton Central7,514Carshalton and Wallington2,2726732,2540108053245,384
SuttonCarshalton South and Clockhouse7,221Carshalton and Wallington2,6055681,895063025175,173
SuttonSt Helier8,885Carshalton and Wallington1,8351,7142,74905043206,366
SuttonThe Wrythe7,420Carshalton and Wallington1,8898662,468046032155,316
SuttonWallington North7,928Carshalton and Wallington2,2968682,3390118041185,680
SuttonWallington South7,625Carshalton and Wallington2,0917842,3350700125565,461
SuttonWandle Valley8,665Carshalton and Wallington1,8521,7692,492037048116,209
 Total70,848 19,4529,36220,8180501043419050,757

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

Old seat: Sutton and Cheam

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

Old seat: Sutton and CheamTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
SuttonBelmont7,483Carshalton and Wallington3,3279381,2220370005,524
SuttonCheam7,704Sutton and Cheam3,4858271,3330410005,686
SuttonNonsuch7,951Sutton and Cheam3,2529111,6380680005,869
SuttonStonecot7,954Sutton and Cheam2,8991,2421,59701340005,872
SuttonSutton Central8,192Sutton and Cheam2,2661,8291,68002710006,046
SuttonSutton North7,600Sutton and Cheam2,6081,2971,6450610005,611
SuttonSutton South7,092Sutton and Cheam2,6601,1331,3650780005,236
SuttonSutton West7,819Sutton and Cheam2,7141,2841,6830910005,772
SuttonWorcester Park8,608Sutton and Cheam3,3551,2031,7060900006,354
 Total70,403 26,56610,66413,869087100051,970

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

New seat: Carshalton and Wallington

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

New seat: Carshalton and Wallington
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
SuttonBeddington North7,636Carshalton and Wallington2,1839992,217042038195,498
SuttonBeddington South7,734Carshalton and Wallington2,4291,1212,069012029105,670
SuttonBelmont7,275Sutton and Cheam3,3279381,2220370005,524
SuttonCarshalton Central7,529Carshalton and Wallington2,2726732,2540108053245,384
SuttonCarshalton South and Clockhouse7,523Carshalton and Wallington2,6055681,895063025175,173
SuttonSt Helier7,544Carshalton and Wallington1,8351,7142,74905043206,366
SuttonThe Wrythe7,439Carshalton and Wallington1,8898662,468046032155,316
SuttonWallington North7,749Carshalton and Wallington2,2968682,3390118041185,680
SuttonWallington South7,496Carshalton and Wallington2,0917842,3350700125565,461
SuttonWandle Valley7,654Carshalton and Wallington1,8521,7692,492037048116,209
 Total75,579 22,77910,30022,0400538043419056,281

And these are the implied results for 2017 for the new seat of Carshalton and Wallington.


© 2017 Martin Baxter
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