New Seat Details - Plymouth Sutton and Devonport

This page shows the detail of the calculations performed to estimate the general election result for 2017 had the new boundaries for Plymouth Sutton and Devonport 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.

Party	Implied 2017 Votes	Implied 2017 Share
LAB	29,258	49.1%
CON	25,931	43.5%
UKIP	1,732	2.9%
LIB	1,708	2.9%
Green	782	1.3%
OTH	214	0.4%
LAB Majority	3,327	5.6%

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.

Plymouth Sutton and Devonport: Map

List of old seats forming part of Plymouth Sutton and Devonport

Old seat: Devon South West

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

Old seat: Devon South West				Transfer-adjusted Results
District	Ward	Electorate 2017	New Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	NAT Votes	MIN Votes	OTH Votes	Total Votes
Plymouth	Plympton Chaddlewood	5,945	Plympton, Tavistock and Ivybridge	2,648	1,795	180	196	58	0	0	0	4,877
Plymouth	Plympton Erle	6,680	Plympton, Tavistock and Ivybridge	2,829	1,817	311	185	125	0	0	0	5,267
Plymouth	Plympton St Mary	9,973	Plympton, Tavistock and Ivybridge	4,602	2,313	290	266	182	0	0	0	7,653
Plymouth	Plymstock Dunstone	9,465	Plymouth Sutton and Devonport	4,256	2,242	398	264	149	0	0	0	7,309
Plymouth	Plymstock Radford	9,800	Plymouth Sutton and Devonport	4,251	2,534	287	268	97	0	0	0	7,437
South Hams	Bickleigh and Cornwood	2,197	Plympton, Tavistock and Ivybridge	1,097	371	108	24	40	0	0	0	1,640
South Hams	Charterlands	2,217	Plympton, Tavistock and Ivybridge	1,143	377	43	23	45	0	0	0	1,631
South Hams	Ermington and Ugborough	2,195	Plympton, Tavistock and Ivybridge	1,010	359	122	20	38	0	0	0	1,549
South Hams	Ivybridge East	4,201	Plympton, Tavistock and Ivybridge	1,883	1,018	311	110	87	0	0	0	3,409
South Hams	Ivybridge West	4,634	Plympton, Tavistock and Ivybridge	2,444	948	131	60	96	0	0	0	3,679
South Hams	Loddiswell and Aveton Gifford	763	Totnes	375	122	14	7	15	0	0	0	533
South Hams	Newton and Yealmpton	4,785	Plympton, Tavistock and Ivybridge	2,180	802	286	45	94	0	0	0	3,407
South Hams	Wembury and Brixton	3,664	Plympton, Tavistock and Ivybridge	1,761	600	184	39	62	0	0	0	2,646
South Hams	Woolwell	2,215	Plympton, Tavistock and Ivybridge	1,156	519	65	32	47	0	0	0	1,819
	Total	68,734		31,635	15,817	2,730	1,539	1,135	0	0	0	52,856

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

Old seat: Plymouth Sutton and Devonport

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

Old seat: Plymouth Sutton and Devonport				Transfer-adjusted Results
District	Ward	Electorate 2017	New Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	NAT Votes	MIN Votes	OTH Votes	Total Votes
Plymouth	Compton	8,529	Plymouth Sutton and Devonport	2,950	2,520	143	154	60	0	0	14	5,841
Plymouth	Devonport	9,380	Plymouth Sutton and Devonport	2,332	4,044	114	192	71	0	0	22	6,775
Plymouth	Drake	5,504	Plymouth Sutton and Devonport	1,983	2,871	108	119	70	0	0	61	5,212
Plymouth	Efford and Lipson	9,121	Plymouth Sutton and Devonport	2,317	3,846	133	182	70	0	0	26	6,574
Plymouth	Peverell	9,846	Plymouth Moor View	3,052	2,800	220	164	67	0	0	22	6,325
Plymouth	St Peter and the Waterfront	9,221	Plymouth Sutton and Devonport	2,709	4,135	167	197	100	0	0	39	7,347
Plymouth	Stoke	8,796	Plymouth Sutton and Devonport	2,656	3,342	169	175	81	0	0	20	6,443
Plymouth	Sutton and Mount Gould	8,590	Plymouth Sutton and Devonport	2,477	3,724	189	181	84	0	0	32	6,687
	Total	68,987		20,476	27,282	1,243	1,364	603	0	0	236	51,204

The full details of these calculations are given on the Plymouth Sutton and Devonport seat details page. Click on "Show workings".

New seat: Plymouth Sutton and Devonport

District	Ward	Electorate 2017	Old Seat	CON Votes	LAB Votes	LIB Votes	UKIP Votes	Green Votes	NAT Votes	MIN Votes	OTH Votes	Total Votes
New seat: Plymouth Sutton and Devonport
Plymouth	Compton	8,735	Plymouth Sutton and Devonport	2,950	2,520	143	154	60	0	0	14	5,841
Plymouth	Devonport	10,132	Plymouth Sutton and Devonport	2,332	4,044	114	192	71	0	0	22	6,775
Plymouth	Drake	7,796	Plymouth Sutton and Devonport	1,983	2,871	108	119	70	0	0	61	5,212
Plymouth	Efford and Lipson	9,832	Plymouth Sutton and Devonport	2,317	3,846	133	182	70	0	0	26	6,574
Plymouth	Plymstock Dunstone	9,855	Devon South West	4,256	2,242	398	264	149	0	0	0	7,309
Plymouth	Plymstock Radford	10,025	Devon South West	4,251	2,534	287	268	97	0	0	0	7,437
Plymouth	St Peter and the Waterfront	10,988	Plymouth Sutton and Devonport	2,709	4,135	167	197	100	0	0	39	7,347
Plymouth	Stoke	9,637	Plymouth Sutton and Devonport	2,656	3,342	169	175	81	0	0	20	6,443
Plymouth	Sutton and Mount Gould	10,000	Plymouth Sutton and Devonport	2,477	3,724	189	181	84	0	0	32	6,687
	Total	87,000		25,931	29,258	1,708	1,732	782	0	0	214	59,625

And these are the implied results for 2017 for the new seat of Plymouth Sutton and Devonport. Please note that the wards used are those of 2015 in order to be consistent with those used by the Boundary Commissions.

Implied MP at 2017:	Luke Pollard (LAB)
County/Area:	Devon (South West)
Electorate:	87,000
Turnout:	68.5%

Plymouth Sutton and Devonport: New Boundaries 2018 Calculation

Plymouth Sutton and Devonport: Overview

Introduction