Shrewsbury: New Boundaries 2018 Calculation

Shrewsbury: Overview

Projection: CON seat

Implied MP at 2017:Daniel Kawczynski  (CON)
County/Area:Shropshire (West Midlands)
Electorate:81,495
Turnout:73.6%

PartyImplied 2017 VotesImplied 2017 Share
CON30,15150.3%
LAB22,86038.1%
LIB4,5337.6%
UKIP1,3632.3%
Green1,0941.8%
CON Majority7,29112.2%

See overview of other seats in West Midlands.



Introduction

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Shrewsbury 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.

Shrewsbury: Map

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

List of old seats forming part of Shrewsbury

The old seat(s) needed are:

Old seat: Ludlow

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

Old seat: LudlowTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
ShropshireAlveley and Claverley3,338Bridgnorth and The Wrekin1,7494481440260002,367
ShropshireBishop's Castle2,747Ludlow and Leominster1,24350532701140002,189
ShropshireBridgnorth East and Astley Abbotts5,322Bridgnorth and The Wrekin2,4289434640600003,895
ShropshireBridgnorth West and Tasley5,433Bridgnorth and The Wrekin2,5119854570580004,011
ShropshireBroseley3,545Bridgnorth and The Wrekin1,3131,2041730380002,728
ShropshireBrown Clee3,015Ludlow and Leominster1,7744141080300002,326
ShropshireChirbury and Worthen2,302Shrewsbury1,0784162810270001,802
ShropshireChurch Stretton and Craven Arms7,141Ludlow and Leominster3,2241,2886540890005,255
ShropshireClee3,477Ludlow and Leominster1,6856293650350002,714
ShropshireCleobury Mortimer5,614Ludlow and Leominster2,9939422360710004,242
ShropshireClun3,014Ludlow and Leominster1,36851534301190002,345
ShropshireCorvedale2,991Ludlow and Leominster1,773332960270002,228
ShropshireHighley2,574Ludlow and Leominster1,2306162450320002,123
ShropshireLudlow East2,935Ludlow and Leominster1,13085133401130002,428
ShropshireLudlow North2,942Ludlow and Leominster1,17655332601050002,160
ShropshireLudlow South3,047Ludlow and Leominster1,3316554190430002,448
ShropshireMuch Wenlock3,406Ludlow and Leominster1,6805412700400002,531
ShropshireWorfield2,944Bridgnorth and The Wrekin1,749311940250002,179
 Total65,787 31,43512,1485,33601,05200049,971

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

Old seat: Shrewsbury and Atcham

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

Old seat: Shrewsbury and AtchamTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
ShropshireAbbey2,971Shrewsbury1,031629281981010002,140
ShropshireBagley3,339Shrewsbury1,228963277441130002,625
ShropshireBattlefield2,782Shrewsbury1,13887710038260002,179
ShropshireBayston Hill, Column and Sutton9,640Shrewsbury2,8933,312311259900006,865
ShropshireBelle Vue3,270Shrewsbury9071,35714136450002,486
ShropshireBowbrook2,882Shrewsbury1,28683210836320002,294
ShropshireBurnell3,430Shrewsbury1,75957619030330002,588
ShropshireCastlefields and Ditherington3,149Shrewsbury7921,55613142400002,561
ShropshireCopthorne3,030Shrewsbury1,39465017093340002,341
ShropshireHarlescott3,265Shrewsbury9661,64712848350002,824
ShropshireLongden3,108Shrewsbury1,296666240102330002,337
ShropshireLoton3,081Shrewsbury1,58953115529260002,330
ShropshireMeole3,002Shrewsbury1,25797115735350002,455
ShropshireMonkmoor3,108Shrewsbury9521,42313743320002,587
ShropshirePorthill3,399Shrewsbury1,400751335401370002,663
ShropshireQuarry and Coton Hill2,807Shrewsbury1,15578629734490002,321
ShropshireRadbrook3,296Shrewsbury1,30069422936350002,294
ShropshireRea Valley3,143Shrewsbury1,430677133100300002,370
ShropshireSevern Valley3,262Shrewsbury1,72755910227270002,442
ShropshireSundorne3,012Shrewsbury8371,44111940330002,470
ShropshireTern3,567Shrewsbury1,63862717632310002,504
ShropshireUnderdale2,985Shrewsbury1,098919335121500002,523
 Total75,528 29,07322,4444,2521,3631,06700058,199

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

New seat: Shrewsbury

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

New seat: Shrewsbury
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
ShropshireAbbey2,907Shrewsbury and Atcham1,031629281981010002,140
ShropshireBagley3,565Shrewsbury and Atcham1,228963277441130002,625
ShropshireBattlefield2,960Shrewsbury and Atcham1,13887710038260002,179
ShropshireBayston Hill, Column and Sutton9,322Shrewsbury and Atcham2,8933,312311259900006,865
ShropshireBelle Vue3,375Shrewsbury and Atcham9071,35714136450002,486
ShropshireBowbrook3,115Shrewsbury and Atcham1,28683210836320002,294
ShropshireBurnell3,514Shrewsbury and Atcham1,75957619030330002,588
ShropshireCastlefields and Ditherington3,477Shrewsbury and Atcham7921,55613142400002,561
ShropshireChirbury and Worthen2,453Ludlow1,0784162810270001,802
ShropshireCopthorne3,181Shrewsbury and Atcham1,39465017093340002,341
ShropshireHarlescott3,836Shrewsbury and Atcham9661,64712848350002,824
ShropshireLongden3,174Shrewsbury and Atcham1,296666240102330002,337
ShropshireLoton3,164Shrewsbury and Atcham1,58953115529260002,330
ShropshireMeole3,335Shrewsbury and Atcham1,25797115735350002,455
ShropshireMonkmoor3,514Shrewsbury and Atcham9521,42313743320002,587
ShropshirePorthill3,615Shrewsbury and Atcham1,400751335401370002,663
ShropshireQuarry and Coton Hill3,153Shrewsbury and Atcham1,15578629734490002,321
ShropshireRadbrook3,116Shrewsbury and Atcham1,30069422936350002,294
ShropshireRea Valley3,219Shrewsbury and Atcham1,430677133100300002,370
ShropshireSevern Valley3,317Shrewsbury and Atcham1,72755910227270002,442
ShropshireSundorne3,355Shrewsbury and Atcham8371,44111940330002,470
ShropshireTern3,401Shrewsbury and Atcham1,63862717632310002,504
ShropshireUnderdale3,427Shrewsbury and Atcham1,098919335121500002,523
 Total81,495 30,15122,8604,5331,3631,09400060,001

And these are the implied results for 2017 for the new seat of Shrewsbury. 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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