Hertfordshire South West: New Boundaries 2018 Calculation

Hertfordshire South West: Overview

Projection: CON seat

Implied MP at 2017:David Gauke  (CON)
County/Area:Hertfordshire (Anglia)
Electorate:72,673
Turnout:75.4%

PartyImplied 2017 VotesImplied 2017 Share
CON32,93860.1%
LAB12,81923.4%
LIB6,49111.9%
Green1,4862.7%
UKIP1,0411.9%
CON Majority20,11936.7%

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 Hertfordshire South West 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.

Hertfordshire South West: Map

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

List of old seats forming part of Hertfordshire South West

The old seat(s) needed are:

Old seat: Hemel Hempstead

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

Old seat: Hemel HempsteadTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
DacorumAdeyfield East3,661Hemel Hempstead1,5141,0271200470002,708
DacorumAdeyfield West3,970Hemel Hempstead1,3891,3352820310003,037
DacorumApsley and Corner Hall6,199Hemel Hempstead2,4771,65026601070004,500
DacorumAshridge2,095Hertfordshire South West1,010325570260001,418
DacorumBennetts End4,320Hemel Hempstead1,6441,4691800720003,365
DacorumBoxmoor6,475Hemel Hempstead2,5501,45635901120004,477
DacorumChaulden and Warners End6,469Hemel Hempstead2,5091,8422630900004,704
DacorumGadebridge3,867Hemel Hempstead1,5301,1901380580002,916
DacorumGrovehill5,203Hemel Hempstead2,2081,6182140920004,132
DacorumHemel Hempstead Town3,822Hemel Hempstead1,3441,3542100410002,949
DacorumHighfield3,723Hemel Hempstead1,3481,3323180740003,072
DacorumKings Langley3,930Hemel Hempstead1,7627621530580002,735
DacorumLeverstock Green6,748Hemel Hempstead2,9361,5252370990004,797
DacorumNash Mills2,350Hemel Hempstead899536650300001,530
DacorumWatling4,135Hemel Hempstead1,9107841380270002,859
DacorumWoodhall Farm3,728Hemel Hempstead1,7061,0842340590003,083
 Total70,695 28,73619,2893,23401,02300052,282

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

Old seat: Hertfordshire South West

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

Old seat: Hertfordshire South WestTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
DacorumAldbury and Wigginton1,839Hertfordshire South West81330819816590001,394
DacorumBerkhamsted Castle4,548Hertfordshire South West1,995724488411460003,394
DacorumBerkhamsted East4,368Hertfordshire South West1,818985495391530003,490
DacorumBerkhamsted West4,411Hertfordshire South West2,043930333381430003,487
DacorumBovingdon, Flaunden and Chipperfield6,276Hertfordshire South West3,620968348671970005,200
DacorumNorthchurch2,127Hertfordshire South West1,01736214622650001,612
DacorumTring Central3,822Hertfordshire South West1,670763430421280003,033
DacorumTring East2,149Hertfordshire South West1,02037522947310001,702
DacorumTring West and Rural4,017Hertfordshire South West1,624752448911300003,045
Three RiversCarpenders Park1,383Watford55833310236160001,045
Three RiversChorleywood North and Sarratt5,848Hertfordshire South West2,92467625299510004,002
Three RiversChorleywood South and Maple Cross5,728Hertfordshire South West2,6191,00266455710004,411
Three RiversDickinsons5,147Hertfordshire South West1,9631,000590113650003,731
Three RiversDurrants5,026Hertfordshire South West1,812937580118560003,503
Three RiversMoor Park and Eastbury4,571Hertfordshire South West2,53052519617390003,307
Three RiversOxhey Hall and Hayling2,589Watford99877125669330002,127
Three RiversPenn and Mill End5,063Hertfordshire South West2,0821,197608129590004,075
Three RiversRickmansworth Town5,369Hertfordshire South West2,378990429107670003,971
Three RiversSouth Oxhey4,537Watford1,6431,978286147680004,122
 Total78,818 35,12715,5767,0781,2931,57700060,651

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

New seat: Hertfordshire South West

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

New seat: Hertfordshire South West
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
DacorumAldbury and Wigginton1,846Hertfordshire South West81330819816590001,394
DacorumAshridge2,035Hemel Hempstead1,010325570260001,418
DacorumBerkhamsted Castle4,495Hertfordshire South West1,995724488411460003,394
DacorumBerkhamsted East4,620Hertfordshire South West1,818985495391530003,490
DacorumBerkhamsted West4,617Hertfordshire South West2,043930333381430003,487
DacorumBovingdon, Flaunden and Chipperfield6,884Hertfordshire South West3,620968348671970005,200
DacorumNorthchurch2,134Hertfordshire South West1,01736214622650001,612
DacorumTring Central4,016Hertfordshire South West1,670763430421280003,033
DacorumTring East2,252Hertfordshire South West1,02037522947310001,702
DacorumTring West and Rural4,030Hertfordshire South West1,624752448911300003,045
Three RiversChorleywood North and Sarratt5,297Hertfordshire South West2,92467625299510004,002
Three RiversChorleywood South and Maple Cross5,840Hertfordshire South West2,6191,00266455710004,411
Three RiversDickinsons4,940Hertfordshire South West1,9631,000590113650003,731
Three RiversDurrants4,637Hertfordshire South West1,812937580118560003,503
Three RiversMoor Park and Eastbury4,378Hertfordshire South West2,53052519617390003,307
Three RiversPenn and Mill End5,395Hertfordshire South West2,0821,197608129590004,075
Three RiversRickmansworth Town5,257Hertfordshire South West2,378990429107670003,971
 Total72,673 32,93812,8196,4911,0411,48600054,775

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