Gravesham: New Boundaries 2018 Calculation

Gravesham: Overview

Projection: CON seat

Implied MP at 2017:Adam Holloway  (CON)
County/Area:Kent (South East)
Electorate:77,368
Turnout:67.3%

PartyImplied 2017 VotesImplied 2017 Share
CON29,53256.7%
LAB18,42535.4%
UKIP1,8703.6%
LIB1,2612.4%
Green7461.4%
OTH2170.4%
CON Majority11,10721.3%

See overview of other seats in South East.



Introduction

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

Gravesham: Map

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

List of old seats forming part of Gravesham

The old seat(s) needed are:

Old seat: Dartford

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

Old seat: DartfordTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
DartfordBean and Darenth4,165Dartford1,81396756139230093,007
DartfordBrent4,903Dartford2,0241,1611041473500103,481
DartfordCastle1,833Dartford85741746701300101,413
DartfordGreenhithe5,042Dartford2,0591,0731031434200293,449
DartfordHeath5,021Dartford2,06497991160310053,330
DartfordJoyce Green3,642Dartford1,0351,14271125720052,450
DartfordJoydens Wood5,617Dartford2,53785583178320063,691
DartfordLittlebrook3,106Dartford9561,14660117260042,309
DartfordLongfield, New Barn and Southfleet5,639Dartford2,389597551508200283,301
DartfordNewtown5,112Dartford1,9401,4721361731200093,850
DartfordPrinces4,312Dartford1,5851,45285153340073,316
DartfordStone4,803Dartford1,7871,34780171340073,426
DartfordSutton-at-Hone and Hawley3,265Dartford1,45058349108200092,219
DartfordSwanscombe4,822Dartford1,8921,7001001994300363,970
DartfordTown2,708Dartford1,10889386116740052,282
DartfordWest Hill4,981Dartford1,9811,200123172870063,569
DartfordWilmington3,209Dartford1,4375085094180032,110
SevenoaksHartley and Hodsoll Street4,731Gravesham2,296533511302200213,053
 Total76,911 31,21018,0251,4292,5458080020954,226

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

Old seat: Gravesham

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

Old seat: GraveshamTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
GraveshamCentral4,477Gravesham1,8501,251851363800113,371
GraveshamChalk1,727Gravesham7162263052100071,041
GraveshamColdharbour3,196Gravesham1,0471,03869108260082,296
GraveshamHigham3,138Gravesham1,3894253638160051,909
GraveshamIstead Rise2,841Gravesham1,23827139761500101,649
GraveshamMeopham North3,485Gravesham1,5723585390180062,097
GraveshamMeopham South and Vigo3,434Gravesham1,62034742941700132,133
GraveshamNorthfleet North4,742Gravesham1,6001,794881629400163,754
GraveshamNorthfleet South5,055Gravesham1,5921,791101799500103,668
GraveshamPainters Ash4,363Gravesham1,5431,0717261690082,824
GraveshamPelham4,667Gravesham1,8231,680917710200113,784
GraveshamRiverside4,842Gravesham1,7582,16386914200204,160
GraveshamRiverview3,370Gravesham1,400478651055000202,118
GraveshamShorne, Cobham and Luddesdown3,243Gravesham1,5493103986190092,012
GraveshamSinglewell5,280Gravesham1,7731,372891703300173,454
GraveshamWestcourt4,555Gravesham1,4701,6846973300093,335
GraveshamWhitehill3,115Gravesham1,24570062101210072,136
GraveshamWoodlands4,947Gravesham2,05193394141290093,257
 Total70,477 27,23617,8921,2101,7407240019648,998

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

New seat: Gravesham

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

New seat: Gravesham
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
GraveshamCentral5,019Gravesham1,8501,251851363800113,371
GraveshamChalk1,552Gravesham7162263052100071,041
GraveshamColdharbour3,419Gravesham1,0471,03869108260082,296
GraveshamHigham2,841Gravesham1,3894253638160051,909
GraveshamIstead Rise2,456Gravesham1,23827139761500101,649
GraveshamMeopham North3,121Gravesham1,5723585390180062,097
GraveshamMeopham South and Vigo3,176Gravesham1,62034742941700132,133
GraveshamNorthfleet North5,589Gravesham1,6001,794881629400163,754
GraveshamNorthfleet South5,463Gravesham1,5921,791101799500103,668
GraveshamPainters Ash4,204Gravesham1,5431,0717261690082,824
GraveshamPelham5,633Gravesham1,8231,680917710200113,784
GraveshamRiverside6,192Gravesham1,7582,16386914200204,160
GraveshamRiverview3,152Gravesham1,400478651055000202,118
GraveshamShorne, Cobham and Luddesdown2,994Gravesham1,5493103986190092,012
GraveshamSinglewell5,143Gravesham1,7731,372891703300173,454
GraveshamWestcourt4,964Gravesham1,4701,6846973300093,335
GraveshamWhitehill3,179Gravesham1,24570062101210072,136
GraveshamWoodlands4,851Gravesham2,05193394141290093,257
SevenoaksHartley and Hodsoll Street4,420Dartford2,296533511302200213,053
 Total77,368 29,53218,4251,2611,8707460021752,051

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