Scottish Boundaries 2005 Example: Dunbartonshire East

First posted 8 July 2004

This page is a worked example for the new constituency of Dunbartonshire East, following the method described by the general calculation method.

The new seat of Dunbartonshire East is made up of parts of the old seats of Strathkelvin and Bearsden, and Clydebank and Milngavie. We start by looking at the old seat of Strathkelvin and Bearsden. Its 2001 General Election result is

NameElectionElectorateCONLABLIBSNPSSPOTH
Strathkelvin & BearsdenGeneral62,7296,63519,2507,5336,6751,3930

We now look at the local election results for 2003 in this constituency. We can break the constituency up into two parts, called West and East. The West side, made up of 14 wards, will form part of the new seat of Dunbartonshire East. The East side, 5 wards, will go into Cumbernauld, Kilsyth and Kirkintilloch East. The election results were:

NameElectionElectorateCONLABLIBSNPSSPOTH
West sideLocal48,5476,5947,1819,6303,6551,0940
East sideLocal17,9006205,3647011,4609140
TotalLocal66,4477,21412,54510,3315,1152,0080

We can now calculate the implied 2001 results using the calculation formula. We begin with the Conservatives. As their local result (7,214 votes) is larger than their general election result (6,635 votes) we use the (multiplicative) formula:

West side Implied CON = 6,594 x 6,635 / 7,214 = 6,065
East side Implied CON = 620 x 6,635 / 7,214 = 570

For Labour, we follow the more usual (additive) formula, since their general election score was higher than their local election total. Their implied votes are:

West side Implied LAB = 7,181 + (19,250 - 12,545) x 48,547 / 66,447 = 12,080
East side Implied LAB = 5,364 + (19,250 - 12,545) x 17,900 / 66,447 = 7,170

We repeat this procedure for the other parties. The Liberal Democrats and the SSP use the multiplicative formula, and the SNP use the additive formula. The end result is the implied votes for both sides of Strathkelvin and Bearsden of:

NameElectionElectorateCONLABLIBSNPSSPOTH
West sideImplied48,5476,06512,0807,0224,7957590
East sideImplied17,9005707,1705111,8806340
TotalImplied66,4476,63519,2507,5336,6751,3930

We note that the total implied votes are exactly equal to the actual general election result. This is important if we are to allocate votes properly.

Clydebank and Milngavie

We can perform similar calculations on the old seat of Clydebank and Milngavie, which also divides into two parts. We call these parts Milngavie (5 wards, which will go into Dunbartonshire East) and Clydebank (11 wards, which will go into Dunbartonshire West). The equivalent table is:

NameElectionElectorateCONLABLIBSNPSSPOTH
Clydebank and MilngavieGeneral52,5343,51417,2493,9096,5251,2940
MilngavieImplied17,3912,1833,7083,3631,0722940
ClydebankImplied35,1431,33113,5415465,4531,0000
TotalImplied52,5343,51417,2493,9096,5251,2940

Dunbartonshire East is created

By taking the west side of Strathkelvin and Bearsden, along with the Milngavie part of Clydebank and Milngavie we have the total implied results for Dunbartonshire East:

NameElectionElectorateCONLABLIBSNPSSPOTH
West sideImplied48,5476,06512,0807,0224,7957590
MilngavieImplied17,3912,1833,7083,3631,0722940
Dunbartonshire EastImplied66,7248,24815,78710,3855,8671,0530

It is interesting that this particular seat, although made out of parts of two very strongly Labour seats, is more marginal than either of those seats. This follows from the disproportionate Liberal Democrat and Conservative strength in the parts of the old seats which are transferred into this new one.

Appendix: Ward breakdown

The west side of Strathkelvin and Bearsden is made up of the 14 wards:

Bearsden; Castlehill/Thorn; Chapleton; Westerton; W Kirkintilloch & Torrance; Kirkintilloch C; Lenzie; S Lenzie; Kenmure & Baldernock; Bamuildy & Park; Cadder/Langbrae; Auchinairn & Crowhill; Woodhill W; Woodhill E.

The east side is made up of the five wards:

Hillhead & Broomhill; Rosebank & Waterside; E Harestanes & Twechar; Campsie; Milton.

© Electoral Calculus