Bradford South East and Spen: New Boundaries 2018 Calculation

Bradford South East and Spen: Overview

Projection: LAB seat

Implied MP at 2017:Tracy Brabin  (LAB)
County/Area:West Yorkshire (Yorks/Humber)
Electorate:75,052
Turnout:65.1%

PartyImplied 2017 VotesImplied 2017 Share
LAB25,61952.4%
CON20,28041.5%
LIB1,0362.1%
MIN6651.4%
UKIP6361.3%
Green5791.2%
OTH310.1%
LAB Majority5,33910.9%

See overview of other seats in Yorks/Humber.



Introduction

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Bradford South East and Spen 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.

Bradford South East and Spen: Map

Boundary Lines courtesy of Ordnance Survey OpenData © Crown copyright 2015, Map © OpenStreetMap contributors

List of old seats forming part of Bradford South East and Spen

The old seat(s) needed are:

Old seat: Batley and Spen

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

Old seat: Batley and SpenTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
KirkleesBatley East12,092Batley and Morley2,6836,34516301180238139,560
KirkleesBatley West12,663Batley and Morley2,8266,05717201150272159,457
KirkleesBirstall and Birkenshaw12,155Bradford South East and Spen4,1883,6431810106010258,225
KirkleesCleckheaton12,719Bradford South East and Spen3,5444,2513130119016498,400
KirkleesHeckmondwike12,803Bradford South East and Spen3,1885,2351680117014088,856
KirkleesLiversedge and Gomersal13,529Bradford South East and Spen4,4544,3132270120016099,283
 Total75,961 20,88329,8441,224069501,0765953,781

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

Old seat: Bradford South

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

Old seat: Bradford SouthTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
BradfordGreat Horton9,911Bradford South3,1983,649782096204907,245
BradfordQueensbury11,681Calderdale South and Queensbury2,9612,970953056108806,480
BradfordRoyds11,258Bradford South2,5204,047993377007507,148
BradfordTong10,217Bradford South East and Spen2,6204,987783616402408,134
BradfordWibsey10,027Bradford South2,0793,521982726106506,096
BradfordWyke9,874Bradford South East and Spen2,2863,190692755307505,948
 Total62,968 15,66422,3645171,7593710376041,051

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

New seat: Bradford South East and Spen

The new seat of Bradford South East and Spen is made up of the following wards, with the transfer-adjusted votes shown.

New seat: Bradford South East and Spen
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
BradfordTong13,424Bradford South2,6204,987783616402408,134
BradfordWyke9,817Bradford South2,2863,190692755307505,948
KirkleesBirstall and Birkenshaw12,258Batley and Spen4,1883,6431810106010258,225
KirkleesCleckheaton12,521Batley and Spen3,5444,2513130119016498,400
KirkleesHeckmondwike13,198Batley and Spen3,1885,2351680117014088,856
KirkleesLiversedge and Gomersal13,834Batley and Spen4,4544,3132270120016099,283
 Total75,052 20,28025,6191,03663657906653148,846

And these are the implied results for 2017 for the new seat of Bradford South East and Spen. Please note that the wards used are those of 2015 in order to be consistent with those used by the Boundary Commissions.


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