Chatham and The Mallings: New Boundaries 2018 Calculation

Chatham and The Mallings: Overview

 Projection: CON seat 

Implied MP at 2017: Tracey Crouch  (CON)
County/Area: Kent (South East)
Electorate: 73,954
Turnout: 69.6%

 Implied 2017 VotesImplied 2017 Share
CON29,52257.4%
LAB16,30731.7%
UKIP2,4814.8%
LIB2,1674.2%
Green7551.5%
OTH2370.5%
CON Majority13,21525.7%

See overview of other seats in South East.

Chatham and The Mallings : Political and Demographic indicators

The table below shows some political and demographic numerical indicators for the new Chatham and The Mallings constituency, the 'South East' 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.

IndicatorSeatSouth EastAll GB
Party WinnerCONCONCON
Economic Position7° Right4° Right
National Position11° Nat3° Nat1° Int
EU Leave %62%52%52%
British Identity31%29%29%
Good Health48%49%48%
UK Born82%88%88%
Good Education40%43%39%
Good Job57%56%51%
High SEC58%57%51%
Average Age47.249.248.5
ABC1 Class58%60%53%

Chatham and The Mallings ranks #110 for "Leave", #164 for "Right" and #102 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

Chatham and The Mallings: 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 Chatham and The Mallings 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 Chatham and The Mallings

The old seat(s) needed are:

Old seat: Chatham and Aylesford

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

Old seat: Chatham and AylesfordTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
MedwayChatham Central11,901Chatham and The Mallings3,1683,8152838411500767,586
MedwayLordswood and Capstone6,537Gillingham and Rainham2,7391,204721161500234,169
MedwayLuton and Wayfield10,407Chatham and The Mallings3,0082,866296633100376,634
MedwayPrinces Park7,580Chatham and The Mallings2,7361,527504455700164,831
MedwayWalderslade6,968Chatham and The Mallings2,6841,3151012814400174,442
Tonbridge and MallingAylesford North and Walderslade4,606Chatham and The Mallings2,21661833253300112,936
Tonbridge and MallingAylesford South3,074Chatham and The Mallings1,5052951074360061,962
Tonbridge and MallingBurham and Wouldham1,950Chatham and The Mallings7693552694000431,242
Tonbridge and MallingDitton3,427Chatham and The Mallings1,45652564211140042,184
Tonbridge and MallingLarkfield North3,476Chatham and The Mallings1,43150623016270062,216
Tonbridge and MallingLarkfield South3,106Chatham and The Mallings1,17847221947570061,979
Tonbridge and MallingSnodland East and Ham Hill3,655Chatham and The Mallings1,25983191127130092,330
Tonbridge and MallingSnodland West and Holborough Lakes3,732Chatham and The Mallings1,4368016649220062,380
 Total70,419 25,58515,1301,1162,2265740026044,891

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

Old seat: Tonbridge and Malling

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

Old seat: Tonbridge and MallingTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
SevenoaksCowden and Hever1,611Tonbridge8452303051310001,187
SevenoaksEdenbridge North and East3,600Tonbridge1,815519129531370002,653
SevenoaksEdenbridge South and West3,348Tonbridge1,519608761401240002,467
SevenoaksLeigh and Chiddingstone Causeway1,742Tonbridge1,0701302233300001,285
SevenoaksPenshurst, Fordcombe and Chiddingstone1,926Tonbridge8921892577740001,419
Tonbridge and MallingBorough Green and Long Mill5,386Tonbridge2,2701,3031421071460003,968
Tonbridge and MallingCage Green3,576Tonbridge1,747524164791210002,635
Tonbridge and MallingCastle3,882Tonbridge1,785456386162170002,860
Tonbridge and MallingDowns and Mereworth3,288Tonbridge1,82635637841190002,422
Tonbridge and MallingEast Malling3,964Chatham and The Mallings1,333760619140690002,921
Tonbridge and MallingHadlow and East Peckham5,640Tonbridge2,885760952211940004,155
Tonbridge and MallingHigham3,719Tonbridge1,859574131451320002,741
Tonbridge and MallingHildenborough3,847Tonbridge1,904453261841320002,834
Tonbridge and MallingJudd4,036Tonbridge1,4849142951371440002,974
Tonbridge and MallingKings Hill6,058Chatham and The Mallings3,37886465113430004,463
Tonbridge and MallingMedway4,243Tonbridge1,8509161041061490003,125
Tonbridge and MallingTrench3,758Tonbridge1,466879163188730002,769
Tonbridge and MallingVauxhall3,922Tonbridge1,524882304301510002,891
Tonbridge and MallingWateringbury1,631Tonbridge8732391325520001,202
Tonbridge and MallingWest Malling and Leybourne4,564Chatham and The Mallings1,965757439118840003,363
Tonbridge and MallingWrotham, Ightham and Stansted3,493Sevenoaks1,92839854791140002,573
 Total77,234 36,21812,7113,7861,8562,33600056,907

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

New seat: Chatham and The Mallings

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

New seat: Chatham and The Mallings
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
MedwayChatham Central8,996Chatham and Aylesford3,1683,8152838411500767,586
MedwayLuton and Wayfield8,936Chatham and Aylesford3,0082,866296633100376,634
MedwayPrinces Park6,837Chatham and Aylesford2,7361,527504455700164,831
MedwayWalderslade6,956Chatham and Aylesford2,6841,3151012814400174,442
Tonbridge and MallingAylesford North and Walderslade4,948Chatham and Aylesford2,21661833253300112,936
Tonbridge and MallingAylesford South3,180Chatham and Aylesford1,5052951074360061,962
Tonbridge and MallingBurham and Wouldham2,065Chatham and Aylesford7693552694000431,242
Tonbridge and MallingDitton3,707Chatham and Aylesford1,45652564211140042,184
Tonbridge and MallingEast Malling3,527Tonbridge and Malling1,333760619140690002,921
Tonbridge and MallingKings Hill5,645Tonbridge and Malling3,37886465113430004,463
Tonbridge and MallingLarkfield North3,402Chatham and Aylesford1,43150623016270062,216
Tonbridge and MallingLarkfield South3,228Chatham and Aylesford1,17847221947570061,979
Tonbridge and MallingSnodland East and Ham Hill3,476Chatham and Aylesford1,25983191127130092,330
Tonbridge and MallingSnodland West and Holborough Lakes4,257Chatham and Aylesford1,4368016649220062,380
Tonbridge and MallingWest Malling and Leybourne4,794Tonbridge and Malling1,965757439118840003,363
 Total73,954 29,52216,3072,1672,4817550023751,469

And these are the implied results for 2017 for the new seat of Chatham and The Mallings.


© 2017 Martin Baxter
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