Hertsmere: New Boundaries 2018 Calculation

Hertsmere: Overview

Projection: CON seat

Implied MP at 2017:Oliver Dowden  (CON)
County/Area:Hertfordshire (Anglia)
Electorate:80,651
Turnout:71.7%

PartyImplied 2017 VotesImplied 2017 Share
CON34,31059.4%
LAB16,76129.0%
LIB4,1167.1%
UKIP1,5622.7%
Green1,0571.8%
CON Majority17,54930.4%

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 Hertsmere 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.

Hertsmere: Map

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

List of old seats forming part of Hertsmere

The old seat(s) needed are:

Old seat: Hertsmere

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

Old seat: HertsmereTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
HertsmereAldenham East3,639Hertsmere1,93138115381430002,589
HertsmereAldenham West3,437Hertsmere1,81946916343480002,542
HertsmereBorehamwood Brookmeadow4,927Hertsmere2,1731,61419090780004,145
HertsmereBorehamwood Cowley Hill5,584Hertsmere2,0481,981184105840004,402
HertsmereBorehamwood Hillside6,243Hertsmere2,6361,796240288940005,054
HertsmereBorehamwood Kenilworth3,987Hertsmere1,5691,24413974610003,087
HertsmereBushey Heath4,742Hertsmere2,70659512856570003,542
HertsmereBushey North3,462Hertsmere1,9921,10425980760003,511
HertsmereBushey Park5,622Hertsmere1,62854320747500002,475
HertsmereBushey St James4,936Hertsmere2,3961,088191194800003,949
HertsmereElstree3,648Hertsmere1,9335569541450002,670
HertsmerePotters Bar Furzefield4,841Hertsmere2,010966221214680003,479
HertsmerePotters Bar Oakmere5,212Hertsmere2,2371,26515897780003,835
HertsmerePotters Bar Parkfield5,774Hertsmere2,81084926096800004,095
HertsmereShenley3,771Hertsmere2,04152620556480002,876
 Total69,825 31,92914,9772,7931,56299000052,251

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

Old seat: St Albans

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

Old seat: St AlbansTransfer-adjusted Results
DistrictWardElectorate
2017
New SeatCON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
St AlbansAshley5,344St Albans1,6411,3081,6060770004,632
St AlbansBatchwood5,128St Albans1,7601,4621,2150680004,505
St AlbansClarence4,887St Albans1,5458151,5870680004,015
St AlbansColney Heath4,228St Albans1,4036141,4070470003,471
St AlbansCunningham4,525St Albans1,3829551,4290590003,825
St AlbansLondon Colney6,642Hertsmere2,3811,7841,3230670005,555
St AlbansMarshalswick North4,820St Albans1,7196351,3880550003,797
St AlbansMarshalswick South5,118St Albans2,0797901,3480660004,283
St AlbansPark Street5,464St Albans2,0457401,4320530004,270
St AlbansSopwell4,950St Albans1,3491,4531,4260710004,299
St AlbansSt Peters5,512St Albans2,0051,1481,1870870004,427
St AlbansSt Stephen5,183St Albans2,2144891,0780430003,824
St AlbansVerulam5,260St Albans1,9754791,2150560003,725
Three RiversAbbots Langley and Bedmond1,080St Albans36414730004000815
Three RiversGade Valley1,968Hemel Hempstead710319521070001,557
 Total70,109 24,57213,13818,462082800057,000

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

New seat: Hertsmere

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

New seat: Hertsmere
DistrictWardElectorate
2017
Old Seat CON
Votes
LAB
Votes
LIB
Votes
UKIP
Votes
Green
Votes
NAT
Votes
MIN
Votes
OTH
Votes
Total
Votes
HertsmereAldenham East3,644Hertsmere1,93138115381430002,589
HertsmereAldenham West3,579Hertsmere1,81946916343480002,542
HertsmereBorehamwood Brookmeadow5,835Hertsmere2,1731,61419090780004,145
HertsmereBorehamwood Cowley Hill6,198Hertsmere2,0481,981184105840004,402
HertsmereBorehamwood Hillside7,113Hertsmere2,6361,796240288940005,054
HertsmereBorehamwood Kenilworth4,346Hertsmere1,5691,24413974610003,087
HertsmereBushey Heath4,985Hertsmere2,70659512856570003,542
HertsmereBushey North4,943Hertsmere1,9921,10425980760003,511
HertsmereBushey Park3,484Hertsmere1,62854320747500002,475
HertsmereBushey St James5,559Hertsmere2,3961,088191194800003,949
HertsmereElstree3,759Hertsmere1,9335569541450002,670
HertsmerePotters Bar Furzefield4,899Hertsmere2,010966221214680003,479
HertsmerePotters Bar Oakmere5,398Hertsmere2,2371,26515897780003,835
HertsmerePotters Bar Parkfield5,765Hertsmere2,81084926096800004,095
HertsmereShenley4,047Hertsmere2,04152620556480002,876
St AlbansLondon Colney7,097St Albans2,3811,7841,3230670005,555
 Total80,651 34,31016,7614,1161,5621,05700057,806

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