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 Arundel and South Downs 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.

List of old seats forming part of Arundel and South Downs

Old seat: Chichester

The raw vote table shows the district council election results for all the wards in the old seat of Chichester. 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: Chichester				Actual Results				Turnout-adjusted Results
District	Ward	Election Year	Electorate 2010	CON Votes	LAB Votes	LIB Votes	OTH Votes	CON Votes	LAB Votes	LIB Votes	OTH Votes	Total Votes
Chichester	Bosham	2011	3,469	2,138	314	476	0	1,758	258	391	0	2,407
Chichester	Boxgrove	2011	1,792	624	103	0	175	861	142	0	241	1,244
Chichester	Chichester East	2011	5,875	0	705	3,270	0	0	723	3,355	0	4,078
Chichester	Chichester North	2011	5,064	3,969	444	2,174	257	2,039	228	1,117	132	3,516
Chichester	Chichester South	2011	5,184	2,359	392	2,778	0	1,535	255	1,808	0	3,598
Chichester	Chichester West	2011	3,805	1,176	304	1,354	201	1,023	265	1,178	175	2,641
Chichester	Donnington	2011	1,793	682	0	0	221	940	0	0	305	1,245
Chichester	Easebourne	2011	1,962	552	106	285	0	797	153	412	0	1,362
Chichester	East Wittering	2011	4,165	2,070	458	0	0	2,367	524	0	0	2,891
Chichester	Fernhurst	2011	3,974	2,005	247	740	412	1,625	200	600	334	2,759
Chichester	Fishbourne	2011	1,856	403	0	571	0	533	0	755	0	1,288
Chichester	Funtington	2011	2,163	-1	0	0	0	1,502	0	0	0	1,502
Chichester	Harting	2011	1,671	0	0	0	-1	0	0	0	1,160	1,160
Chichester	Lavant	2011	1,758	316	94	448	0	449	134	637	0	1,220
Chichester	Midhurst	2011	4,015	1,495	201	747	768	1,298	174	648	667	2,787
Chichester	North Mundham	2011	1,745	509	0	325	0	739	0	472	0	1,211
Chichester	Plaistow	2011	3,802	2,105	0	939	221	1,702	0	759	179	2,640
Chichester	Rogate	2011	2,020	990	97	0	0	1,277	125	0	0	1,402
Chichester	Selsey North	2011	5,153	3,420	550	0	450	2,768	445	0	364	3,577
Chichester	Selsey South	2011	3,542	1,856	280	0	369	1,822	275	0	362	2,459
Chichester	Sidlesham	2011	1,928	477	0	329	0	792	0	546	0	1,338
Chichester	Southbourne	2011	5,621	3,416	346	2,041	318	2,178	221	1,301	203	3,903
Chichester	Stedham	2011	1,778	772	187	0	0	994	241	0	0	1,235
Chichester	Tangmere	2011	1,914	618	201	0	0	1,003	326	0	0	1,329
Chichester	West Wittering	2011	3,985	2,647	243	361	486	1,959	180	267	360	2,766
Chichester	Westbourne	2011	1,770	515	0	345	0	736	0	493	0	1,229
	Total		81,804					32,697	4,869	14,739	4,482	56,787

The transfer table below shows the votes cast in the old seat of Chichester 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.

Party	General Election 2010 Votes	Local Election Turnout-adjusted Votes	Votes to transfer away	Votes to transfer into	Ward Transfers needed
CON	31,427	32,697	1,270	0	Transfer away 3.9% (= 1270 / 32697) of ward's CON votes
LAB	5,937	4,869	0	1,068	Transfer in 56.8% (= 1068 / 1879) of ward's transfer pool votes
LIB	15,550	14,739	0	811	Transfer in 43.2% (= 811 / 1879) of ward's transfer pool votes
OTH	3,873	4,482	609	0	Transfer away 13.6% (= 609 / 4482) of ward's OTH votes
Total	56,787	56,787	1,879	1,879

Main table for Chichester

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

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

Old seat: Arundel and South Downs

Old seat: Chichester	Transfer-adjusted Results
District	Ward	Electorate 2010	New Seat	CON Votes	LAB Votes	LIB Votes	OTH Votes	Total Votes
Chichester	Bosham	3,469	Chichester	1,690	297	420	0	2,407
Chichester	Boxgrove	1,792	Chichester	828	180	29	208	1,244
Chichester	Chichester East	5,875	Chichester	0	723	3,355	0	4,078
Chichester	Chichester North	5,064	Chichester	1,960	283	1,159	114	3,516
Chichester	Chichester South	5,184	Chichester	1,475	289	1,834	0	3,598
Chichester	Chichester West	3,805	Chichester	983	301	1,205	151	2,641
Chichester	Donnington	1,793	Chichester	903	44	34	264	1,245
Chichester	Easebourne	1,962	Chichester	766	171	425	0	1,362
Chichester	East Wittering	4,165	Chichester	2,275	576	40	0	2,891
Chichester	Fernhurst	3,974	Chichester	1,562	262	647	289	2,759
Chichester	Fishbourne	1,856	Chichester	512	12	764	0	1,288
Chichester	Funtington	2,163	Chichester	1,444	33	25	0	1,502
Chichester	Harting	1,671	Chichester	0	90	68	1,002	1,160
Chichester	Lavant	1,758	Chichester	432	144	645	0	1,220
Chichester	Midhurst	4,015	Chichester	1,248	254	709	576	2,787
Chichester	North Mundham	1,745	Chichester	710	16	484	0	1,211
Chichester	Plaistow	3,802	Arundel and South Downs	1,636	51	798	155	2,640
Chichester	Rogate	2,020	Chichester	1,227	153	21	0	1,402
Chichester	Selsey North	5,153	Chichester	2,660	534	68	315	3,577
Chichester	Selsey South	3,542	Chichester	1,751	343	52	313	2,459
Chichester	Sidlesham	1,928	Chichester	761	17	559	0	1,338
Chichester	Southbourne	5,621	Chichester	2,093	285	1,349	175	3,903
Chichester	Stedham	1,778	Chichester	955	263	17	0	1,235
Chichester	Tangmere	1,914	Chichester	964	348	17	0	1,329
Chichester	West Wittering	3,985	Chichester	1,883	251	321	311	2,766
Chichester	Westbourne	1,770	Chichester	707	16	505	0	1,229
	Total	81,804		31,425	5,936	15,550	3,873	56,787

The raw vote table shows the district council election results for all the wards in the old seat of Arundel and South Downs. 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: Arundel and South Downs				Actual Results				Turnout-adjusted Results
District	Ward	Election Year	Electorate 2010	CON Votes	LAB Votes	LIB Votes	OTH Votes	CON Votes	LAB Votes	LIB Votes	OTH Votes	Total Votes
Arun	Angmering	2011	5,870	4,248	538	550	1,041	2,854	361	370	699	4,284
Arun	Arundel	2011	3,497	1,993	347	346	475	1,609	280	279	384	2,552
Arun	Barnham	2011	6,825	5,126	0	1,288	787	3,546	0	891	544	4,981
Arun	Findon	2011	2,115	682	0	181	183	1,007	0	267	270	1,544
Arun	Walberton	2011	2,304	826	0	219	176	1,138	0	302	242	1,682
Chichester	Bury	2011	1,811	672	0	238	112	869	0	308	145	1,322
Chichester	Petworth	2011	3,869	2,334	0	510	400	2,032	0	444	348	2,824
Chichester	Wisborough Green	2011	1,999	768	0	287	0	1,062	0	397	0	1,459
Horsham	Bramber, Upper Beeding and Woodmancote	2011	4,277	1,912	236	1,288	212	1,636	202	1,102	181	3,121
Horsham	Chanctonbury	2011	6,593	5,426	427	550	414	3,830	301	388	292	4,811
Horsham	Chantry	2011	7,682	7,267	661	836	592	4,355	396	501	355	5,607
Horsham	Cowfold, Shermanbury and West Grinstead	2011	4,273	2,369	0	628	0	2,465	0	654	0	3,119
Horsham	Henfield	2011	4,097	986	262	398	1,561	919	244	371	1,456	2,990
Horsham	Pulborough and Coldwaltham	2011	4,991	2,582	240	269	932	2,338	217	244	844	3,643
Horsham	Steyning	2011	5,050	2,020	274	857	1,406	1,634	222	693	1,137	3,686
Mid Sussex	Hassocks	2011	5,775	4,168	542	3,542	340	2,045	266	1,738	167	4,216
Mid Sussex	Hurstpierpoint and Downs	2011	5,669	4,119	0	1,175	2,627	2,152	0	614	1,372	4,138
	Total		76,697					35,491	2,489	9,563	8,436	55,979

The transfer table below shows the votes cast in the old seat of Arundel and South Downs 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.

Party	General Election 2010 Votes	Local Election Turnout-adjusted Votes	Votes to transfer away	Votes to transfer into	Ward Transfers needed
CON	32,333	35,491	3,158	0	Transfer away 8.9% (= 3158 / 35491) of ward's CON votes
LAB	4,835	2,489	0	2,346	Transfer in 27.8% (= 2346 / 8425) of ward's transfer pool votes
LIB	15,642	9,563	0	6,079	Transfer in 72.2% (= 6079 / 8425) of ward's transfer pool votes
OTH	3,172	8,436	5,264	0	Transfer away 62.4% (= 5264 / 8436) of ward's OTH votes
Total	55,982	55,979	8,425	8,425

Main table for Arundel and South Downs

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