Norwich South: New Boundaries 2018 Calculation

Norwich South: Overview

Projection: LAB seat

Implied MP at 2017:Clive Lewis  (LAB)
County/Area:Norfolk (Anglia)
Electorate:75,631
Turnout:69.8%

PartyImplied 2017 VotesImplied 2017 Share
LAB29,86356.5%
CON18,04334.2%
LIB3,4706.6%
Green1,4362.7%
LAB Majority11,82022.4%

See overview of other seats in Anglia.



Introduction

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

Norwich South: Map

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

List of old seats forming part of Norwich South

The old seat(s) needed are:

Old seat: Norfolk South

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

Old seat: Norfolk SouthTransfer-adjusted Results
DistrictWardElectorate
2017		New SeatCON
Votes		LAB
Votes		LIB
Votes		UKIP
Votes		Green
Votes		NAT
Votes		MIN
Votes		OTH
Votes		Total
Votes
South NorfolkBeck Vale1,818Norfolk South839373980610001,371
South NorfolkBressingham and Burston2,228Norfolk South1,128480640840001,756
South NorfolkBrooke2,085Norfolk South1,0854271210260001,659
South NorfolkBunwell2,166Norfolk South1,076517960240001,713
South NorfolkChedgrave and Thurton2,108Norfolk South1,0355271160320001,710
South NorfolkCringleford4,448Norwich South2,0178202820560003,175
South NorfolkDickleburgh2,169Norfolk South1,150441890730001,753
South NorfolkDiss5,757Norfolk South2,4321,66841101950004,706
South NorfolkDitchingham and Broome1,945Norfolk South7564652110260001,458
South NorfolkEarsham1,986Norfolk South8204921910230001,526
South NorfolkEaston2,039Norfolk South1,1124331260290001,700
South NorfolkForncett2,175Norfolk South9954542050270001,681
South NorfolkGillingham2,261Norfolk South1,0445681450300001,787
South NorfolkHarleston3,712Norfolk South1,6319922170470002,887
South NorfolkHempnall2,065Norfolk South1,044459650240001,592
South NorfolkHethersett4,470Norfolk South2,0571,1392710600003,527
South NorfolkLoddon2,182Norfolk South9295421250310001,627
South NorfolkMulbarton4,088Norfolk South1,92894821701350003,228
South NorfolkNewton Flotman2,081Norfolk South9625381280270001,655
South NorfolkOld Costessey6,098Norwich South1,9891,8115770770004,454
South NorfolkPoringland with the Framinghams4,044Norfolk South1,9237822360490002,990
South NorfolkRockland2,308Norfolk South1,0485371510280001,764
South NorfolkRoydon1,837Norfolk South9084851060230001,522
South NorfolkScole1,893Norfolk South950363850620001,460
South NorfolkStoke Holy Cross2,226Norfolk South9005412470950001,783
South NorfolkStratton4,240Norfolk South1,8951,14723201610003,435
South NorfolkTasburgh1,907Norfolk South9304171240240001,495
South NorfolkThurlton2,216Great Yarmouth9955381390270001,699
 Total78,552 35,57818,9045,07501,55600061,113

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

Old seat: Norwich South

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

Old seat: Norwich SouthTransfer-adjusted Results
DistrictWardElectorate
2017		New SeatCON
Votes		LAB
Votes		LIB
Votes		UKIP
Votes		Green
Votes		NAT
Votes		MIN
Votes		OTH
Votes		Total
Votes
NorwichBowthorpe7,872Norwich South1,9333,85726101570006,208
NorwichEaton7,167Norwich South1,9232,29232501260004,666
NorwichLakenham6,709Norwich South1,3223,19232801360004,978
NorwichMancroft7,466Norwich South1,4123,29424801640005,118
NorwichNelson6,650Norwich South1,3443,08235301960004,975
NorwichThorpe Hamlet8,199Norwich South1,9113,18329501600005,549
NorwichTown Close7,968Norwich South1,8103,16536401770005,516
NorwichUniversity5,101Norwich South1,3303,65925201540005,395
NorwichWensum7,705Norwich North1,6784,07923001890006,176
South NorfolkNew Costessey4,126Norwich South1,0521,5081850330002,778
 Total68,963 15,71531,3112,84101,49200051,359

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

New seat: Norwich South

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

New seat: Norwich South
DistrictWardElectorate
2017		Old Seat CON
Votes		LAB
Votes		LIB
Votes		UKIP
Votes		Green
Votes		NAT
Votes		MIN
Votes		OTH
Votes		Total
Votes
NorwichBowthorpe8,966Norwich South1,9333,85726101570006,208
NorwichEaton6,739Norwich South1,9232,29232501260004,666
NorwichLakenham7,191Norwich South1,3223,19232801360004,978
NorwichMancroft7,392Norwich South1,4123,29424801640005,118
NorwichNelson7,186Norwich South1,3443,08235301960004,975
NorwichThorpe Hamlet8,016Norwich South1,9113,18329501600005,549
NorwichTown Close7,968Norwich South1,8103,16536401770005,516
NorwichUniversity7,791Norwich South1,3303,65925201540005,395
South NorfolkCringleford4,316Norfolk South2,0178202820560003,175
South NorfolkNew Costessey4,013Norwich South1,0521,5081850330002,778
South NorfolkOld Costessey6,053Norfolk South1,9891,8115770770004,454
 Total75,631 18,04329,8633,47001,43600052,812

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