What do the academics say? The incumbency effect for MPs

Academics in caps and gowns - Some rights reserved by herkieWelcome to the latest in our occasional series highlighting interesting findings from academic research. Today – the incumbency benefit sitting MPs can build up, based on an analysis of the 1983-2010 general elections:

This note adapts two models commonly used to estimate the incumbency advantage that US members of Congress enjoy – the ‘slurge’ and the Gelman-King Index – to provide comparable estimates for UK MPs. The results show that Liberal Democrats enjoy extremely large such advantages on a par with those of US Congressmen of between 5% and 15% of the vote. Labour and the Conservatives have incumbency advantages at around 2% and 1% respectively. The note estimates that effects could have changed the outcome in as many as 25 seats in some elections, and that they cost the Conservatives the chance to govern alone after the 2010 election.

The piece goes on to explain those two methods of measurement in more detail. The slurge is:

It was observed that in districts where a sitting Congressman stood down and was replaced by a newcomer the sitting party would underperform. When the new Congressman had completed his or her first term, the in party’s vote would surge back up. Slurge takes the mean of this observed retirement slump and the first term ‘sophomore surge’ seen by the parties at each election.

As for Gelman-King, it is a regression equation based on changes in vote share, whether there is an incumbent and who wins.

Aside from the point quoted above about Liberal Democrat MPs having by far the biggest incumbency bonus, the analysis also finds a strong double-incumbency effect for new MPs who have taken seats off other parties. When up for re-election for the first time they now both have their own incumbency bonus and also are up against a rival party which has lost its incumbency bonus, giving a double bonus:

The double incumbency term is particularly strong at the 1997 election, showing that first term Labour MPs who took a seat off the Conservatives in 1992 outperformed other first term Labour MPs by 2.9%, and gaining a first term surge of 4.3%. Conservative MPs who took seats off Labour in 1983 and 1987 did similarly well at the end of their first terms.

You can read (a little) more about Timothy Hallam Smith’s article (and buy access to it for $19.95) here.

You can read the other posts in our What do the academics say? series here.

* Mark Pack has written 101 Ways To Win An Election and produces a monthly newsletter about the Liberal Democrats.

Read more by or more about .
This entry was posted in What do the academics say?.
Advert

4 Comments

  • The obvious question is why our MPs do so much better ? 2 explanations spring to my mind, a bonus for not being part of the establishment & a difference in how we work.
    If its our anti-establishment credential we can expect to take a hit for being in government.

    The 2nd explanation seems more likely, that we work much harder because we have to, that hasnt changed.

  • Matthew Huntbach 22nd Jan '13 - 3:55pm

    paul barker

    The obvious question is why our MPs do so much better ?

    Also because “But you HAVE a Liberal Democrat MP” tends to be a line that works against the argument “I’m not voting LibDem, it’s a wasted vote” even with people who carried on saying that and believing it right up till the point where a LibDem MP got elected.

  • Ian Sanderson 23rd Jan '13 - 8:59am

    A third thought is that because it’s so much harder to become a LibDem MP than a Labour or Tory one, the overall quality of MPs is higher. One of the things that strikes me when attending Conference is how many good people we have as candidates not yet elected as MPs. The larger parties have many safe seats where, as is sometimes said, you can stick the right label on a feather duster and get it elected.
    Even the few LibDem MPs who have rather colourful reputations tend to be people very well dug in locally before being elected as MPs.

Post a Comment

Lib Dem Voice welcomes comments from everyone but we ask you to be polite, to be on topic and to be who you say you are. You can read our comments policy in full here. Please respect it and all readers of the site.

If you are a member of the party, you can have the Lib Dem Logo appear next to your comments to show this. You must be registered for our forum and can then login on this public site with the same username and password.

To have your photo next to your comment please signup your email address with Gravatar.

Your email is never published. Required fields are marked *

*
*
Please complete the name of this site, Liberal Democrat ...?

Advert



Recent Comments

  • User AvatarNigel Ashton 16th Jan - 9:38pm
    Liberal HQ deliberately didn't support the Newcastle-under-Lyme by-election in 1986 because the candidate, Alan Thomas, was a unilateralist. Not, alas, the only case of HQ...
  • User Avatarethicsgradient 16th Jan - 9:36pm
    @Tim13 Hi, I get what your saying and I'm not trying to make assumptions how various generations or individuals in generations might vote. What I...
  • User AvatarTim13 16th Jan - 9:29pm
    Ethicsgradient I know anecdotal evidence on small samples doesn't really cut it, but I and many friends in my generation (baby boom, I am 69)...
  • User AvatarTim13 16th Jan - 9:20pm
    Andrew T never a truer word - "the media has switched sides". Your other comments may have less validity - older leave voters saying "they...
  • User AvatarDave Page 16th Jan - 8:54pm
    Eddie, you seem to be under the misapprehension that this isn't standard practice and hasn't been done countless times before.
  • User AvatarCllr Fran Oborski 16th Jan - 8:33pm
    As a long time member of Hereford and Worcester Fire and Rescue Authority I am appalled at the idea of "privatising" Fire and Rescue Services....