During the campaign, the headline Electoral Calculus prediction is calculated using the Regional Predictor, and you should use that if you want to use the same regional model. See the next section for details.
The methodology we use is described fully in the analysis article on Regional Swing
So far in the campaign, there has been one large regional poll conducted by YouGov between 4-11 April 2010, with a total sample size of 28,154. As other regional-scale polls are published in the campaign, we will use them to update the regional swing estimates.
The values of the YouGov poll, expressed using the same Regional Swing Analysis notation are shown in the tables below. These show
Note that the Regional Swing Differentials do not show the absolute swing between parties, nor the absolute difference between regions of a party's support. Instead they show the relative change in support of a party across the regions. Note that the sum of Regional Swing Differentials across all the parties in any one region is zero. This is because the total support in a region must be 100%, so the sum of changes must be zero. Additionally, the (weighted) sum over all regions of a single party's Regional Swing Differentials is also zero. This is because the differentials are relative measures of a party's success in regions, not an absolute measure. If a party does relatively well in some regions, it must do relatively worse in others.
|(3) Regional Swing|
2005 - 2010
|(4) Regional Swing Differentials|
2005 - 2010
|Scotland||1||-1||-7||6||0||835||-5.0||4.5||-2.8||6.2||-2.9||Strong SNP and Lab gain over the rest|
|The North||7||-10||-3||6||377||0.8||-4.9||0.9||3.1||Others gain over Lab|
|North West||9||-6||-6||3||977||2.8||-0.9||-2.1||0.1||Con gain over LibDem|
|Yorks/Humber||5||-8||-1||3||883||-0.9||-2.4||3.2||0.2||LibDem gain over Lab|
|Wales||9||-5||-4||-2||2||510||2.8||0.1||-0.1||-2.0||-0.9||Con gain over PC|
|West Midlands||9||-9||-2||1||749||3.2||-3.5||2.1||-1.8||Con and LibDem gain over Lab|
|East Midlands||8||-7||-2||2||663||1.4||-2.2||1.8||-1.0||LibDem gain over Lab|
|Anglia||8||-7||-4||3||859||1.8||-1.9||-0.1||0.1||Con gain over Lab|
|South West||0||-1||-2||2||860||-5.8||4.4||2.3||-0.9||Strong Lab and LibDem over Con|
|London||6||-4||-6||4||1223||-0.2||1.1||-2.1||1.1||LibDem lose ground|
|South East||7||-3||-6||2||1331||0.9||2.1||-2.1||-0.9||Lab gain over LibDem|
We see the following trends:
|Party||Relative Gain||Relative Loss|
|CON||North West, Wales, |
|Scotland, South West|
|LAB||Scotland, South West,|
West Midlands, East Midlands
|LIB||Yorks/Humber, West Midlands,|
|North West, London,|
Overall there continues to be some "depolarisation" as parties lose ground in their heartlands and make relative gains elsewhere.
You can make predictions based on these Regional Swing figures by going to the Regional Predictor, entering national support in the boxes marked "National Support", and pressing the buttons marked "Use YouGov Swing", and then "Predict Election". This is the same method that is used for the headline website prediction during the campaign.
Betting markets have the advantage that people are putting their own money at risk, which forces them to think clearly and make use of all possible information available to them. The markets also provide a useful function of taking an average over all (active) opinion on the subject to get a consensus view. The market is also forward-looking, compared with the backward-looking opinion polls.
To use betting markets to help make our prediction, we perform the following steps
For instance, the Sporting Index betting market showed the following prices as at 24 April 2010.
|Party||Bid Seats||Offer Seats|
This has mid-prices of 311, 223 and 83 seats respectively (rounding up in all cases). We can then repeatedly experiment with the Regional Predictor to find the solution point (Con 36.7%, Lab 27.4%, Lib 25.6%):
|Party||2005 Votes||2005 Seats||Pred Votes||Gains||Losses||Pred Seats|
This is a close match to the mid-market seats, so these support percentages are the market-implied figures.
During the campaign we regularly calculate the market-implied support figures. These usually show the Conservatives a little higher than the opinion polls, and Labour a little lower. This is consistent with the long-term pro-Labour bias in the opinion polls. To partially correct for this bias, we add the market-implied figures into our poll-of-polls. This "market poll" is given a sample size of 10,000 which means it will be weighted around 50:50 with the regular opinion polls.