Bromsgrove and Droitwich: New Boundaries 2018 Calculation

Bromsgrove and Droitwich: Overview

 Projection: CON seat 

Implied MP at 2017: Sajid Javid  (CON)
County/Area: Hereford and Worcestershire (West Midlands)
Electorate: 77,216
Turnout: 76.0%

 Implied 2017 VotesImplied 2017 Share
CON35,70060.8%
LAB18,17131.0%
LIB3,1255.3%
Green1,0661.8%
UKIP6241.1%
CON Majority17,52929.9%

See overview of other seats in West Midlands.

Bromsgrove and Droitwich : Political and Demographic indicators

The table below shows some political and demographic numerical indicators for the new Bromsgrove and Droitwich constituency, the 'West Midlands' 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.

IndicatorSeatWest MidlandsAll GB
Party WinnerCONCONCON
Economic Position9° Right2° Right
National Position9° Nat9° Nat1° Int
EU Leave %55%59%52%
British Identity26%28%29%
Good Health45%45%48%
UK Born96%89%88%
Good Education36%35%39%
Good Job49%48%51%
High SEC53%46%51%
Average Age52.748.748.5
ABC1 Class53%49%53%

Bromsgrove and Droitwich ranks #258 for "Leave", #125 for "Right" and #142 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

Bromsgrove and Droitwich: 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 Bromsgrove and Droitwich 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 Bromsgrove and Droitwich

The old seat(s) needed are:

Old seat: Bromsgrove

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

Old seat: BromsgroveTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
BromsgroveAlvechurch South2,260Redditch1,326268460200001,660
BromsgroveAlvechurch Village2,054Redditch9693306601440001,509
BromsgroveAston Fields2,634Bromsgrove and Droitwich1,0956676601060001,934
BromsgroveAvoncroft2,350Bromsgrove and Droitwich1,077574600150001,726
BromsgroveBarnt Green and Hopwood2,291Redditch1,1763691240140001,683
BromsgroveBelbroughton and Romsley5,168Bromsgrove and Droitwich2,906781670420003,796
BromsgroveBromsgrove Central2,592Bromsgrove and Droitwich1,125646970360001,904
BromsgroveCatshill North2,356Bromsgrove and Droitwich900720450640001,729
BromsgroveCatshill South2,210Bromsgrove and Droitwich896647550260001,624
BromsgroveCharford2,699Bromsgrove and Droitwich898987860120001,983
BromsgroveCofton1,918Redditch8573797001030001,409
BromsgroveDrakes Cross2,445Redditch1,292388930220001,795
BromsgroveHagley East2,131Bromsgrove and Droitwich1,16730882090001,566
BromsgroveHagley West2,764Bromsgrove and Droitwich1,480414130080002,032
BromsgroveHill Top1,849Bromsgrove and Droitwich585711430190001,358
BromsgroveHollywood2,397Redditch1,337338720140001,761
BromsgroveLickey Hills2,155Bromsgrove and Droitwich1,061165353030001,582
BromsgroveLowes Hill2,707Bromsgrove and Droitwich1,087821570230001,988
BromsgroveMarlbrook2,329Bromsgrove and Droitwich1,1374194901050001,710
BromsgroveNorton2,118Bromsgrove and Droitwich978474400640001,556
BromsgrovePerryfields1,105Bromsgrove and Droitwich51625031015000812
BromsgroveRock Hill2,622Bromsgrove and Droitwich9558291270150001,926
BromsgroveRubery North2,453Birmingham Northfield829932200220001,803
BromsgroveRubery South2,539Birmingham Northfield922896380100001,866
BromsgroveSanders Park2,723Bromsgrove and Droitwich964915930290002,001
BromsgroveSidemoor2,646Bromsgrove and Droitwich8509571060310001,944
BromsgroveSlideslow2,948Bromsgrove and Droitwich1,4325231510590002,165
BromsgroveTardebigge2,783Bromsgrove and Droitwich1,420505300900002,045
BromsgroveWythall East2,237Redditch1,18538269090001,645
BromsgroveWythall West2,089Redditch1,0723291230100001,534
 Total73,572 33,49416,9242,48901,13900054,046

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

Old seat: Worcestershire Mid

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

Old seat: Worcestershire MidTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
WychavonBadsey2,201Evesham9384845984290001,594
WychavonBengeworth4,333Evesham1,962751852121280003,138
WychavonBowbrook2,215Evesham1,0103122622190001,605
WychavonBretforton and Offenham2,037Evesham87729823338290001,475
WychavonBroadway and Wickhamford3,706Evesham2,08137513115820002,684
WychavonDodderhill2,033Bromsgrove and Droitwich99829115812130001,472
WychavonDrakes Broughton1,924Evesham1,187116505350001,393
WychavonDroitwich Central2,103Bromsgrove and Droitwich67961790120180001,524
WychavonDroitwich East4,382Bromsgrove and Droitwich1,863962202113340003,174
WychavonDroitwich South East4,189Bromsgrove and Droitwich2,09858923469440003,034
WychavonDroitwich South West3,890Bromsgrove and Droitwich1,530838254133630002,818
WychavonDroitwich West4,346Bromsgrove and Droitwich1,4811,4504384910003,149
WychavonEvesham North4,064Evesham1,6078281931981170002,943
WychavonEvesham South4,288Evesham2,150653110521400003,105
WychavonFladbury2,190Evesham1,0922911418550001,587
WychavonGreat Hampton1,968Evesham76738265163480001,425
WychavonHartlebury2,155Bromsgrove and Droitwich1,0903458333110001,562
WychavonHarvington and Norton2,100Evesham1,1152844112690001,521
WychavonHoneybourne and Pebworth2,023Evesham1,2171544535150001,466
WychavonLittle Hampton4,194Evesham1,909771711751120003,038
WychavonLovett and North Claines4,418Bromsgrove and Droitwich2,36859917740160003,200
WychavonNorton and Whittington2,331Worcester1,468126682240001,688
WychavonOmbersley1,895Bromsgrove and Droitwich1,0641671162050001,372
WychavonPinvin2,396Evesham9743783509240001,735
WychavonThe Littletons2,572Evesham1,23339575221390001,864
WychavonUpton Snodsbury2,112Evesham1,2101891164100001,529
 Total76,065 35,96812,6453,4521,6601,37000055,095

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

New seat: Bromsgrove and Droitwich

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

New seat: Bromsgrove and Droitwich
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
BromsgroveAston Fields2,492Bromsgrove1,0956676601060001,934
BromsgroveAvoncroft2,424Bromsgrove1,077574600150001,726
BromsgroveBelbroughton and Romsley5,193Bromsgrove2,906781670420003,796
BromsgroveBromsgrove Central2,363Bromsgrove1,125646970360001,904
BromsgroveCatshill North2,208Bromsgrove900720450640001,729
BromsgroveCatshill South2,174Bromsgrove896647550260001,624
BromsgroveCharford2,318Bromsgrove898987860120001,983
BromsgroveHagley East2,044Bromsgrove1,16730882090001,566
BromsgroveHagley West2,680Bromsgrove1,480414130080002,032
BromsgroveHill Top1,778Bromsgrove585711430190001,358
BromsgroveLickey Hills2,242Bromsgrove1,061165353030001,582
BromsgroveLowes Hill2,565Bromsgrove1,087821570230001,988
BromsgroveMarlbrook2,395Bromsgrove1,1374194901050001,710
BromsgroveNorton2,058Bromsgrove978474400640001,556
BromsgrovePerryfields1,385Bromsgrove51625031015000812
BromsgroveRock Hill2,414Bromsgrove9558291270150001,926
BromsgroveSanders Park2,671Bromsgrove964915930290002,001
BromsgroveSidemoor2,530Bromsgrove8509571060310001,944
BromsgroveSlideslow2,635Bromsgrove1,4325231510590002,165
BromsgroveTardebigge2,209Bromsgrove1,420505300900002,045
WychavonDodderhill2,129Worcestershire Mid99829115812130001,472
WychavonDroitwich Central1,930Worcestershire Mid67961790120180001,524
WychavonDroitwich East4,257Worcestershire Mid1,863962202113340003,174
WychavonDroitwich South East4,185Worcestershire Mid2,09858923469440003,034
WychavonDroitwich South West3,862Worcestershire Mid1,530838254133630002,818
WychavonDroitwich West3,747Worcestershire Mid1,4811,4504384910003,149
WychavonHartlebury2,152Worcestershire Mid1,0903458333110001,562
WychavonLovett and North Claines4,230Worcestershire Mid2,36859917740160003,200
WychavonOmbersley1,946Worcestershire Mid1,0641671162050001,372
 Total77,216 35,70018,1713,1256241,06600058,686

And these are the implied results for 2017 for the new seat of Bromsgrove and Droitwich.


© 2017 Martin Baxter
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