Somerset North: New Boundaries 2013 Calculation

This page shows the detail of the calculations performed to estimate the general election result for 2010 had the new boundaries for Somerset North 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 2010. 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.

Due to changes in ward boundaries, some new wards are divided among several old constituencies (and sometimes in Scotland between two new constituencies). Such wards are shown divided into several parts, called [1], [2], and so on.

Election results from a recent local election are given. This is usually the local election closest to 2010 from the period 2007-2011. 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. Where zero votes are shown, the ward results have not yet been acquired, and the implied result is still provisional and will be improved later.

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% of its votes from each ward. 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 on a ward-by-ward basis using these common percentages.

More details of the calculation formulas are available.

List of old seats forming part of Somerset North

The old seat(s) needed are:

Old seat: Somerset North

Workings for Somerset North

The raw vote table shows the district council election results for all the wards in the old seat of Somerset North. The first block shows the actual results, the second block shows the turnout-adjusted results. Details of the transfer calculation are given below this table.

Old seat: Somerset NorthActual ResultsTurnout-adjusted Results
DistrictWardElection
Year
Electorate
2010
CON
Votes
LAB
Votes
LIB
Votes
Other
Votes
CON
Votes
LAB
Votes
LIB
Votes
Other
Votes
Total
Votes
North SomersetBackwell20114,588778003,205664002,7353,399
North SomersetClevedon Central20112,492445403181079872332501,846
North SomersetClevedon East20112,607338232062254837601,0081,932
North SomersetClevedon North20112,168733337001,100506001,606
North SomersetClevedon South20112,44649948500919893001,812
North SomersetClevedon Walton20112,33391723324501,13628930301,728
North SomersetClevedon West20112,442558304034283845705141,809
North SomersetClevedon Yeo20112,47855029014901,02153827701,836
North SomersetEaston-in-Gordano20112,232729004591,015006391,654
North SomersetGordano20113,1841,09327624301,59940435602,359
North SomersetNailsea East20115,3622,19238702,9741,56827702,1273,972
North SomersetNailsea North and West20117,5894,3121,7031,0582,7422,4709756061,5705,621
North SomersetPill20112,7870001,1890002,0642,064
North SomersetPortishead Central20113,031675051801,270097502,245
North SomersetPortishead Coast20112,384854039101,211055501,766
North SomersetPortishead East20114,2439043214301391,5845627532443,143
North SomersetPortishead Redcliffe Bay20112,689799051501,211078101,992
North SomersetPortishead South and North Weston20112,401604208279098533945501,779
North SomersetPortishead West20112,58172820132301,11230749301,912
North SomersetWinford20112,48534300774565001,2751,840
North SomersetWraxall and Long Ashton20116,0882,6296316481,8172,0714975101,4314,509
North SomersetWrington20112,38261306730841092301,764
North SomersetYatton20117,2312,9291,1571,3282,8091,9087548651,8305,357
 Total 78,223    26,4347,8978,17715,43757,945

The transfer table below shows the votes cast in the old seat of Somerset North at the general election, as well as the total local turnout-adjusted votes. The number of votes to transfer, shown in the fourth and fifth columns, are the difference between the general and local votes. Strong parties will have votes transferred away, and weak parties will have votes transferred into them. The final column describes how votes will be transferred away from or into that party on a ward-by-ward basis. If a party is too strong, it will lose a percentage of its votes in each ward which go into that ward's transfer pool. If a party is too weak, it will gain votes from each ward's transfer pool in proportion to the number of transfer votes it needs over the whole old seat.

PartyGeneral
Election 2010
Votes
Local Election
Turnout-adjusted
Votes
Votes to
transfer
away
Votes to
transfer
into
Ward Transfers needed
CON28,54926,43402,115Transfer in 14.5% (= 2115 / 14625) of ward's transfer pool votes
LAB6,4487,8971,4490Transfer away 18.3% (= 1449 / 7897) of ward's LAB votes
LIB20,6878,177012,510Transfer in 85.5% (= 12510 / 14625) of ward's transfer pool votes
Other2,25715,43713,1800Transfer away 85.4% (= 13180 / 15437) of ward's Other votes
Total57,94157,94514,62514,625 

Main table for Somerset North

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

Old seat: Somerset NorthTransfer-adjusted Results
DistrictWardElectorate
2010
New SeatCON
Votes
LAB
Votes
LIB
Votes
Other
Votes
Total
Votes
North SomersetBackwell4,588Somerset North1,00201,9974003,399
North SomersetClevedon Central2,492Somerset North81759043801,845
North SomersetClevedon East2,607Somerset North6823077951471,931
North SomersetClevedon North2,168Somerset North1,1134137901,605
North SomersetClevedon South2,446Somerset North94372914001,812
North SomersetClevedon Walton2,333Somerset North1,14423634801,728
North SomersetClevedon West2,442Somerset North914373447751,809
North SomersetClevedon Yeo2,478Somerset North1,03543936101,835
North SomersetEaston-in-Gordano2,232Somerset North1,0940467931,654
North SomersetGordano3,184Somerset North1,61033041902,359
North SomersetNailsea East5,362Somerset North1,8382261,5973113,972
North SomersetNailsea North and West7,589Somerset North2,6907961,9062305,622
North SomersetPill2,787Somerset North25501,5073022,064
North SomersetPortishead Central3,031Somerset North1,270097502,245
North SomersetPortishead Coast2,384Somerset North1,211055501,766
North SomersetPortishead East4,243Somerset North1,6294591,019363,143
North SomersetPortishead Redcliffe Bay2,689Somerset North1,211078101,992
North SomersetPortishead South and North Weston2,401Somerset North99427750801,779
North SomersetPortishead West2,581Somerset North1,12025154101,912
North SomersetWinford2,485Somerset North72209311861,839
North SomersetWraxall and Long Ashton6,088Somerset North2,2614061,6332094,509
North SomersetWrington2,382Somerset North841092301,764
North SomersetYatton7,231Somerset North2,1546162,3202685,358
 Total78,223 28,5506,44820,6872,25757,945

After transfer adjustment, the totals for each party over all the wards match the general election vote in the old seat.

New seat: Somerset North

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

New seat: Somerset North
DistrictWardElectorate
2010
Old Seat CON
Votes
LAB
Votes
LIB
Votes
Other
Votes
Total
Votes
North SomersetBackwell4,588Somerset North1,00201,9974003,399
North SomersetClevedon Central2,492Somerset North81759043801,846
North SomersetClevedon East2,607Somerset North6823077951471,932
North SomersetClevedon North2,168Somerset North1,1134137901,606
North SomersetClevedon South2,446Somerset North94372914001,812
North SomersetClevedon Walton2,333Somerset North1,14423634801,728
North SomersetClevedon West2,442Somerset North914373447751,809
North SomersetClevedon Yeo2,478Somerset North1,03543936101,836
North SomersetEaston-in-Gordano2,232Somerset North1,0940467931,654
North SomersetGordano3,184Somerset North1,61033041902,359
North SomersetNailsea East5,362Somerset North1,8382261,5973113,972
North SomersetNailsea North and West7,589Somerset North2,6907961,9062305,621
North SomersetPill2,787Somerset North25501,5073022,064
North SomersetPortishead Central3,031Somerset North1,270097502,245
North SomersetPortishead Coast2,384Somerset North1,211055501,766
North SomersetPortishead East4,243Somerset North1,6294591,019363,143
North SomersetPortishead Redcliffe Bay2,689Somerset North1,211078101,992
North SomersetPortishead South and North Weston2,401Somerset North99427750801,779
North SomersetPortishead West2,581Somerset North1,12025154101,912
North SomersetWinford2,485Somerset North72209311861,840
North SomersetWraxall and Long Ashton6,088Somerset North2,2614061,6332094,509
North SomersetWrington2,382Somerset North841092301,764
North SomersetYatton7,231Somerset North2,1546162,3202685,357
 Total78,223 28,5506,44820,6872,25757,942

This seat was actually unchanged by the Boundary Commission, so these calculations are shown for information only. The actual general election result for 2010 should be used for this seat.