Today in Britain we have a very clear picture of political opinion in the general population. By surveying a nationally representative sample of citizens, researchers regularly make accurate inferences regarding, for example, what proportion of British voters approve of a specific policy, or which political issue is most important to the largest number of Britons.
Yet when we zoom in to look at political opinion at the level of the Parliamentary constituency, the picture is not nearly as clear. For even though they are the basic unit of representation in British politics, each choosing a single Member of Parliament (MP) to send to Westminster, we have very little systematic information about political opinion in individual constituencies. This is because gathering such information using traditional polling techniques is prohibitively expensive: researchers would need to survey a sufficient number of voters in each separate constituency, meaning an extremely large overall sample size.
This all matters because we need to measure political opinion at the constituency-level if we are to answer fundamental questions about the role of constituencies in British representative democracy. For example, is there a meaningful representative link between individual MPs in the House of Commons and their constituents? To what extent do the personal political preferences or political behaviour of individual MPs reflect not just the wishes of the national political party to which they belong, but also political opinion in the constituency they represent? And also, how do changes to constituency boundaries impact upon the electoral fortunes of political parties?
So far, research concerning these questions has been hampered by a lack of direct measures of political opinion in constituencies. Our project will remedy this situation. We will exploit major recent methodological advances which have enabled political scientists in the US and Germany to estimate political opinion for multiple small local areas without having to survey an unfeasibly large overall sample of respondents. Instead, these new methods combine information from several existing, publicly available data sources. First, we use data from the British Election Study, which records the political opinions, socio-demographic type and constituency location of a large number of survey respondents, to estimate a statistical model predicting an individual’s political opinions as a function of their socio-demographic type and constituency location. We also include Ordinance Survey data on which constituencies neighbour each other, thus allowing for the tendency of people who live in constituencies near to one another to have more similar political opinions than those who live in constituencies further apart.
In the second step we generate an estimate of public opinion in each constituency by combining the predictions of our statistical model with Census-based information on the number of people of each socio-demographic type living in that constituency.
Through this procedure, we will generate the first systematic constituency-specific measures of: public opinion on specific political issues such as the Iraq War or European Union membership; and opinion on over-arching political questions such as the appropriate balance between government taxation and spending or which is the most important issue facing the UK.