Filton and Bradley Stoke: New Boundaries 2018 Calculation

Filton and Bradley Stoke: Overview

Projection: CON seat

Implied MP at 2017:Jack Lopresti  (CON)
County/Area:Bristol area (South West)
Electorate:78,600
Turnout:70.2%

PartyImplied 2017 VotesImplied 2017 Share
CON27,86050.5%
LAB21,66139.2%
LIB4,4598.1%
Green1,2132.2%
CON Majority6,19911.2%

See overview of other seats in South West.



Introduction

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Filton and Bradley Stoke 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.

Filton and Bradley Stoke: Map

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

List of old seats forming part of Filton and Bradley Stoke

The old seat(s) needed are:

Old seat: Filton and Bradley Stoke

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

Old seat: Filton and Bradley StokeTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
South GloucestershireAlmondsbury3,254Filton and Bradley Stoke1,4046981250280002,255
South GloucestershireBradley Stoke Central and Stoke Lodge5,717Filton and Bradley Stoke2,3851,6223150670004,389
South GloucestershireBradley Stoke North2,835Filton and Bradley Stoke1,1519131510360002,251
South GloucestershireBradley Stoke South6,137Filton and Bradley Stoke2,6481,9703180750005,011
South GloucestershireDownend8,777Filton and Bradley Stoke3,2002,3103600920005,962
South GloucestershireFilton7,506Filton and Bradley Stoke2,3882,79429903110005,792
South GloucestershireFrenchay and Stoke Park4,058Filton and Bradley Stoke1,8851,4432370670003,632
South GloucestershirePatchway7,613Filton and Bradley Stoke2,0572,5492970800004,983
South GloucestershirePilning and Severn Beach2,777Filton and Bradley Stoke1,1946711060260001,997
South GloucestershireStaple Hill5,683Filton and Bradley Stoke1,4272,2831880630003,961
South GloucestershireStoke Gifford9,029Filton and Bradley Stoke3,2712,57040602620006,509
South GloucestershireWinterbourne6,069Filton and Bradley Stoke2,3211,3252490550003,950
 Total69,455 25,33121,1483,05101,16200050,692

The full details of these calculations are given on the Filton and Bradley Stoke seat details page. Click on "Show workings".

Old seat: Thornbury and Yate

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

Old seat: Thornbury and YateTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
South GloucestershireBoyd Valley5,815Kingswood2,8295611,1190560004,565
South GloucestershireCharfield3,145Dursley, Thornbury and Yate1,6121941,0140300002,850
South GloucestershireChipping Sodbury5,454Dursley, Thornbury and Yate2,3534751,3050570004,190
South GloucestershireCotswold Edge2,725Dursley, Thornbury and Yate1,2751136400200002,048
South GloucestershireDodington5,778Dursley, Thornbury and Yate2,2688741,7160610004,919
South GloucestershireFrampton Cotterell6,040Filton and Bradley Stoke2,5295131,4080510004,501
South GloucestershireLadden Brook3,101Dursley, Thornbury and Yate1,4722216530250002,371
South GloucestershireSevern3,010Dursley, Thornbury and Yate1,7191273560220002,224
South GloucestershireThornbury North6,178Dursley, Thornbury and Yate2,5015791,4830710004,634
South GloucestershireThornbury South and Alveston5,982Dursley, Thornbury and Yate2,4815181,4670640004,530
South GloucestershireWesterleigh3,164Dursley, Thornbury and Yate1,3521797170250002,273
South GloucestershireYate Central6,406Dursley, Thornbury and Yate2,1277531,6520610004,593
South GloucestershireYate North8,771Dursley, Thornbury and Yate3,4911,0032,4080900006,992
 Total65,569 28,0096,11015,938063300050,690

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

New seat: Filton and Bradley Stoke

The new seat of Filton and Bradley Stoke is made up of the following wards, with the transfer-adjusted votes shown.

New seat: Filton and Bradley Stoke
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
South GloucestershireAlmondsbury3,229Filton and Bradley Stoke1,4046981250280002,255
South GloucestershireBradley Stoke Central and Stoke Lodge6,282Filton and Bradley Stoke2,3851,6223150670004,389
South GloucestershireBradley Stoke North3,222Filton and Bradley Stoke1,1519131510360002,251
South GloucestershireBradley Stoke South7,175Filton and Bradley Stoke2,6481,9703180750005,011
South GloucestershireDownend8,536Filton and Bradley Stoke3,2002,3103600920005,962
South GloucestershireFilton8,293Filton and Bradley Stoke2,3882,79429903110005,792
South GloucestershireFrampton Cotterell6,031Thornbury and Yate2,5295131,4080510004,501
South GloucestershireFrenchay and Stoke Park5,200Filton and Bradley Stoke1,8851,4432370670003,632
South GloucestershirePatchway7,135Filton and Bradley Stoke2,0572,5492970800004,983
South GloucestershirePilning and Severn Beach2,858Filton and Bradley Stoke1,1946711060260001,997
South GloucestershireStaple Hill5,668Filton and Bradley Stoke1,4272,2831880630003,961
South GloucestershireStoke Gifford9,317Filton and Bradley Stoke3,2712,57040602620006,509
South GloucestershireWinterbourne5,654Filton and Bradley Stoke2,3211,3252490550003,950
 Total78,600 27,86021,6614,45901,21300055,193

And these are the implied results for 2017 for the new seat of Filton and Bradley Stoke. 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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