Preston: New Boundaries 2018 Calculation

Preston: Overview

Projection: LAB seat

Implied MP at 2017:Mark Hendrick  (LAB)
County/Area:Lancashire (North West)
Electorate:80,341
Turnout:64.8%

PartyImplied 2017 VotesImplied 2017 Share
LAB31,00459.6%
CON16,57531.9%
LIB2,4434.7%
UKIP1,3462.6%
Green6701.3%
LAB Majority14,42927.7%

See overview of other seats in North West.



Introduction

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

Preston: Map

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

List of old seats forming part of Preston

The old seat(s) needed are:

Old seat: Preston

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

Old seat: PrestonTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
PrestonAshton2,993Preston6578909443190001,703
PrestonBrookfield5,003Preston7211,74862152250002,708
PrestonDeepdale3,595Preston3181,9114336230002,331
PrestonFishwick3,260Preston4271,650344380002,162
PrestonIngol5,038Preston8331,559209160110002,772
PrestonLarches5,410Preston8711,63520276270002,811
PrestonMoor Park2,830Preston4491,2886098280001,923
PrestonPreston Rural East192Lancashire North6447330000117
PrestonRibbleton5,337Preston7072,25260182300003,231
PrestonRiversway3,738Preston6221,48774112330002,328
PrestonSt George's3,171Preston3262,1437549240002,617
PrestonSt Matthew's4,285Preston5262,33358146110003,074
PrestonTown Centre4,749Preston6762,4298258470003,292
PrestonTulketh4,593Preston8821,66880154330002,817
PrestonUniversity1,891Preston4101,1707037320001,719
 Total56,085 8,48924,2101,2061,34935100035,605

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

Old seat: Wyre and Preston North

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

Old seat: Wyre and Preston NorthTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
PrestonCadley3,582Preston1,2881,1483190330002,788
PrestonCollege2,700Preston1,0559731300490002,207
PrestonGarrison5,282Preston1,9631,7232230780003,987
PrestonGreyfriars5,188Preston2,1031,3482960730003,820
PrestonPreston Rural East3,360Lancashire North1,667791750250002,558
PrestonPreston Rural North5,328Lancashire North2,6571,0083140310004,010
PrestonSharoe Green4,679Preston1,7411,6492720860003,748
WyreBourne1,865Blackpool North and Fleetwood678705480300001,461
WyreBreck2,855Blackpool North and Fleetwood1,364782800490002,275
WyreBrock with Catterall3,058Lancashire North1,673677670460002,463
WyreCalder1,676Lancashire North841387410300001,299
WyreCarleton3,522Blackpool North and Fleetwood1,5721,001900540002,717
WyreGarstang5,280Lancashire North2,4181,2321240880003,862
WyreGreat Eccleston3,073Lancashire North1,583649550410002,328
WyreHambleton and Stalmine3,500Lancashire North1,610820630460002,539
WyreHardhorn with High Cross4,967Fylde2,2891,1081140720003,583
WyreMarsh Mill2,304Blackpool North and Fleetwood911694520320001,689
WyreStanah3,673Blackpool North and Fleetwood1,664988950550002,802
WyreTithebarn3,283Fylde1,607753910540002,505
 Total69,175 30,68418,4362,549097200052,641

The full details of these calculations are given on the Wyre and Preston North seat details page. Click on "Show workings".

New seat: Preston

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

New seat: Preston
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
PrestonAshton2,765Preston6578909443190001,703
PrestonBrookfield4,395Preston7211,74862152250002,708
PrestonCadley3,829Wyre and Preston North1,2881,1483190330002,788
PrestonCollege3,032Wyre and Preston North1,0559731300490002,207
PrestonDeepdale3,783Preston3181,9114336230002,331
PrestonFishwick3,510Preston4271,650344380002,162
PrestonGarrison5,479Wyre and Preston North1,9631,7232230780003,987
PrestonGreyfriars5,248Wyre and Preston North2,1031,3482960730003,820
PrestonIngol4,499Preston8331,559209160110002,772
PrestonLarches4,562Preston8711,63520276270002,811
PrestonMoor Park3,120Preston4491,2886098280001,923
PrestonRibbleton5,245Preston7072,25260182300003,231
PrestonRiversway3,778Preston6221,48774112330002,328
PrestonSharoe Green5,150Wyre and Preston North1,7411,6492720860003,748
PrestonSt George's4,246Preston3262,1437549240002,617
PrestonSt Matthew's4,992Preston5262,33358146110003,074
PrestonTown Centre5,344Preston6762,4298258470003,292
PrestonTulketh4,573Preston8821,66880154330002,817
PrestonUniversity2,791Preston4101,1707037320001,719
 Total80,341 16,57531,0042,4431,34667000052,038

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