Who’s written on the MP-constituency opinion link?

If you’ve read the short description of our project that we put up some time ago, you’ll realize that this project tries to produce good estimates of public opinion in British constituencies, and to use those estimates to assess the link between constituents and their MPs.

We’re not operating in a vacuum here. Others have written on the link between constituency opinion and MP behaviour — but they’ve had to rely on very loose proxies for opinion.

Let’s take a 1987 paper on the link between constituency opinion and a series of free votes on abortion, capital punishment, and homosexuality. This paper, by John Hibbing and David Marsh, has to rely on a proxy that others have used — namely, the proportion of Catholics in a constituency. Hibbing and Marsh find that, after controlling for party, MPs in constituencies with a higher proportion of Catholics are more likely to support more socially conservative positions.

So far, this approach hasn’t been greatly improved upon. A more recent (2004) paper by John Baughman, on abortion, has a very nice way of handling votes on abortion (an item response model with a meaningful scale) — but the measurement of constituency opinion relies on two dummies for Catholic-heavy regions (e.g. Strathclyde, Merseyside).

These kinds of proxies — percentage of Catholics, percentage of homeowners, etc., — are used for want of more direct measures of constituency opinion. They are useful indirect measures of constituency opinion on a particular political issue to the extent that membership of different demographic groups tends to go with different opinions on that issue.

The trouble is that the relationship between demographic groups and opinion is by no means a perfect one: Catholics do not have uniform political views, and neither do homeowners. In other words, demographic proxies are very noisy measures of constituency opinion. As a result, when we use these proxies to assess the link between MP behaviour and constituency opinion, the true picture may be obscured or even misrepresented.

Another problem with using demographic proxies for constituency opinion is that there are only a limited number of political issues where peoples’ opinions are strongly associated with their observable social characteristics. Because of this, researchers have been restricted to assessing the MP-constituency link on this limited subset of issues.

In sum, we need better, more specific, measures of public opinion in Westminster constituencies if we want to better understand the link between MPs and their constituents in Britain.

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Presentation for today’s talk at the LSE

Ben Lauderdale presented some of the early results from our project at the LSE’s event on the General Election 2015.

You can find the slides here [PDF].

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It’s a small (area) world

The techniques we’re using on this project belong to a long-lasting and broad tradition called small area estimation.

Small-area estimation has been around since the early eighties. It’s extremely useful if you have considerable information on large units but limited information on smaller units. It’s been used in areas from biology and medicine to economics and social policy.

It’s also something that our funders — the Economic and Social Research Council — have put a lot of support behind. The National Centre for Research Methods has a specialist network dedicated to the topic.

Our methods — which we’ll explain in later posts — fall in to what that special network describes as the “statistical regression-based approach”.

Small area estimation in the study of politics has a long and almost entirely American history, some of which is summarized in a recent and general paper by Jeff Lax and Justin Phillips, How Should We Estimate Public Opinion in the States?. Everything that we do here, however, should be intelligible to epidemiologists and human geographers — as well, of course, as the general public.

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About our project

This is our first post on this site — and we can’t really do anything better than refer you to the About section, where we’ve described, in what we hope are fairly user-friendly terms, what we’re trying to do on this project.

We’ll have lots more posts in the future — roughly one a week — so do follow us on Twitter, or through our RSS feed, if you want to stay up to date with the progress of the project.

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