Do the Lib Dems just want PR because they would be the main beneficiaries?

by endlesspsych

I shamelessly pimped my last blog entry on a thread I started over on badscience and recieved this comment from MJRobbins of the layscientist:

“Nice piece, although I would have liked you to have challenged the Lib Dems a bit, if only for the fact that I suspect one of the real reasons they’re so keen on PR is that they’d be the biggest gainers from it (or is that actually another PR myth?)”

Note how I have shamelessly included the praise for my previous post in the quote. Such vanity aside it raises an interesting point – how much does the Lib dems position on PR hinge on ideology and how much on self interest?

Unfortunately I don’t think that’s a question I will be able to answer. I can however show what the Lib Dems share of the vote is and how many seats this translates to under a PR as opposed FPTP system. Of course to do so I also have to ignore the fact that it’s likely voters intentions and strategies would differ considerably under the two systems and that results would likely not be anywhere near the same… But considering it might make a halfway decent proxy answer to the question without necessarily answering the question I’ve soldered on regardless.

Indeed the BBC politics show East (Living up in Scotland I have no idea if this is what it’s actually called anyone from the vicinity of Norfolk is welcome to correct me) seems to hold the same contention in this article. There is a nice wee diagram that shows the Lib Dems gaining more then double (sounds impressive but that’s only seven seats as opposed to three as near as I can tell from the BBC graphic) which, if I understand the article correctly, relies on a number of assumptions such as Tory voters not giving their second preference vote to Labour and the like. This is based on a number of assumptions which, although probably fairly valid and rational, I intend to ignore for the next bit of this post.

Keele University provides a summary of British general election results since 1945, giving the seats and the percentage of votes won by the main party groupings here. Taking the official founding date of the Liberal Democrats as 1988 I have focused on elections since that date to see if PR would have given them an advantage in terms of seats. (Again ignoring the fact that in all likely hood the results would be at least slightly different under a PR system)

The data, as I haven’t yet learnt how to do such basic formatting things as tables (so apologises for the distinctly comma separated value vibe) is presented as follows:- Year, Percentage of vote, actual seats won, seats that would have been won under PR, difference in seats (Under a simplified system whereby percentage of vote translates directly proportionately (IE 646*0.178 for in the first case) to seats gained).

Lib Dem (Average = +75 seats)

1992,17.8%, 20, 114, +94

1997, 16.8%, 46, 108, +62

2001, 18.3%, 52, 118, +66

2005, 22.0%, 62, 142, +80

That does pretty much show the Lib Dems to be at a fairly large advantage under the PR system (abet with all the aforementioned unrealistic assumptions and using only the simplest of simple maths). For instance the other two major parties votes would shape up as follows:-

Conservative (Average =+4 seats)

1992, 41.9,%, 336, 270, -66

1997, 30.7%, 165, 198, +33

2001, 31.7%, 166, 204, +38

2005, 32.4%, 198, 209, +11

Labour (Average = -115 seats)

1992, 34.4,%, 271, 222, -49

1997, 43.2%, 418, 219, -199

2001, 40.7%, 413, 262, -151

2005, 45.2%, 356, 291, -65

So the Lib Dems, on average, would gain substantially more seats under a PR system with the Conservatives, over the last few elections, also doing a tiny bit better Labour would appear to have the most to lose under this system. Although I suspect that might be an artifact of tactical voting in FPTP combined with being the party in power.

Interestingly no one party, based on my half arsed maths, would have enough MP’s for a simple majority so minority Govt. or coalition seems likely. A PR system might have seen (rather then a Labour majority under FPTP) the Libs sharing power with Labour (which seems most likely) or the Conservatives… Of course I’ve ignored smaller parties which would further obfuscate my working.

But based on this rather simple analysis it would appear that the Lib Dems do have the most to gain from PR. It could after all make them the power brokers…

But as stated this doesn’t actually answer the question as it works on too many flawed assumptions. I do think it illustrates where the “myth” comes from even if it doesn’t really address it’s validity either way. I had fun playing with a calculator if nothing else, plus it was very interesting to see the disparity between popular vote and seats gained. Which has done more to make me support some form of PR then anything else…