New Seat Details - Derbyshire South

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

Party	Implied 2017 Votes	Implied 2017 Share
CON	32,378	58.1%
LAB	20,319	36.5%
LIB	2,071	3.7%
Green	771	1.4%
UKIP	160	0.3%
CON Majority	12,059	21.7%

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.

Derbyshire South: Map

List of old seats forming part of Derbyshire South

Old seat: Derby North

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

Old seat: Derby North				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
Derby	Abbey	8,996	Derby West	2,657	4,278	357	162	0	0	0	0	7,454
Derby	Chaddesden	10,015	Derby East	3,022	3,063	228	176	0	0	0	0	6,489
Derby	Darley	9,931	Derby West	3,327	3,384	369	157	0	0	0	0	7,237
Derby	Derwent	9,243	Derby East	2,540	3,887	249	185	0	0	0	0	6,861
Derby	Littleover	10,645	Derby West	3,330	3,075	403	148	0	0	0	0	6,956
Derby	Mackworth	9,174	Derby West	2,823	3,593	264	193	0	0	0	0	6,873
Derby	Mickleover	11,666	Derbyshire South	3,909	2,344	391	160	0	0	0	0	6,804
	Total	69,670		21,608	23,624	2,261	1,181	0	0	0	0	48,674

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

Old seat: Derbyshire South

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

Old seat: Derbyshire South				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
South Derbyshire	Aston	5,323	Derby East	2,439	965	190	0	144	0	0	0	3,738
South Derbyshire	Church Gresley	5,858	Derbyshire South	2,070	1,728	122	0	61	0	0	0	3,981
South Derbyshire	Etwall	4,246	Derbyshire South	2,294	678	82	0	47	0	0	0	3,101
South Derbyshire	Hatton	1,934	Derbyshire South	830	501	43	0	21	0	0	0	1,395
South Derbyshire	Hilton	6,589	Derbyshire South	3,626	1,453	170	0	80	0	0	0	5,329
South Derbyshire	Linton	3,923	Derbyshire South	1,615	993	128	0	42	0	0	0	2,778
South Derbyshire	Melbourne	4,175	Derbyshire South	1,812	821	148	0	49	0	0	0	2,830
South Derbyshire	Midway	6,031	Derbyshire South	2,347	2,028	162	0	76	0	0	0	4,613
South Derbyshire	Newhall and Stanton	6,169	Derbyshire South	2,166	2,261	140	0	70	0	0	0	4,637
South Derbyshire	Repton	3,886	Derbyshire South	2,289	705	90	0	55	0	0	0	3,139
South Derbyshire	Seales	4,111	Derbyshire South	1,807	1,007	70	0	42	0	0	0	2,926
South Derbyshire	Stenson	3,394	Derbyshire South	1,074	1,187	85	0	36	0	0	0	2,382
South Derbyshire	Swadlincote	5,876	Derbyshire South	2,288	1,891	152	0	69	0	0	0	4,400
South Derbyshire	Willington and Findern	3,635	Derbyshire South	1,664	720	89	0	46	0	0	0	2,519
South Derbyshire	Woodville	6,427	Derbyshire South	2,587	2,002	199	0	77	0	0	0	4,865
	Total	71,577		30,908	18,940	1,870	0	915	0	0	0	52,633

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

New seat: Derbyshire South

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: Derbyshire South
Derby	Mickleover	9,774	Derby North	3,909	2,344	391	160	0	0	0	0	6,804
South Derbyshire	Church Gresley	5,774	Derbyshire South	2,070	1,728	122	0	61	0	0	0	3,981
South Derbyshire	Etwall	4,497	Derbyshire South	2,294	678	82	0	47	0	0	0	3,101
South Derbyshire	Hatton	2,024	Derbyshire South	830	501	43	0	21	0	0	0	1,395
South Derbyshire	Hilton	7,730	Derbyshire South	3,626	1,453	170	0	80	0	0	0	5,329
South Derbyshire	Linton	4,029	Derbyshire South	1,615	993	128	0	42	0	0	0	2,778
South Derbyshire	Melbourne	4,104	Derbyshire South	1,812	821	148	0	49	0	0	0	2,830
South Derbyshire	Midway	6,692	Derbyshire South	2,347	2,028	162	0	76	0	0	0	4,613
South Derbyshire	Newhall and Stanton	6,727	Derbyshire South	2,166	2,261	140	0	70	0	0	0	4,637
South Derbyshire	Repton	4,552	Derbyshire South	2,289	705	90	0	55	0	0	0	3,139
South Derbyshire	Seales	4,243	Derbyshire South	1,807	1,007	70	0	42	0	0	0	2,926
South Derbyshire	Stenson	3,456	Derbyshire South	1,074	1,187	85	0	36	0	0	0	2,382
South Derbyshire	Swadlincote	6,382	Derbyshire South	2,288	1,891	152	0	69	0	0	0	4,400
South Derbyshire	Willington and Findern	3,654	Derbyshire South	1,664	720	89	0	46	0	0	0	2,519
South Derbyshire	Woodville	7,057	Derbyshire South	2,587	2,002	199	0	77	0	0	0	4,865
	Total	80,695		32,378	20,319	2,071	160	771	0	0	0	55,699

And these are the implied results for 2017 for the new seat of Derbyshire South. 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:	Heather Wheeler (CON)
County/Area:	Derbyshire (East Midlands)
Electorate:	80,695
Turnout:	69.0%

Derbyshire South: New Boundaries 2018 Calculation

Derbyshire South: Overview

Introduction