In the second of my series on voting systems (after questioning whether first-past-the-post even qualifies as a democratic electoral system), I now turn my unique eye to the single-transferable-vote.
STV is the favourite voting system of a lot of reformers, most influentially the Electoral Reform Society and the Liberal Democrats.
STV is the voting system used in Ireland, Malta, the Australian Senate (upper house) and...err that's it!* (*Oh, to be fair, it is now also used in Scottish and some New Zealand local government elections as well).
STV is listed amongst the family of voting systems described as proportional representation, although strictly it isn't a PR system, although it can deliver reasonably proportional results (if quota is low enough).
STV is a preferential voting system (like the Alternative Vote - AV is in fact STV in a single constituency), i.e. instead of 'simply' putting an X against one candidate as you do with most List PR voting systems or for electing an MP to Westminster with first-past-the-post, you 'simply' list candidates 1,2,3 in order of preference.
Now, it sounds silly, but some voters will have a problem in writing 1,2,3 on the ballot paper. The spoilt rate will go up, but we are talking about very small numbers here. For those who oppose STV, you would be scraping the barrel using this argument.
I suppose the biggest difficulty with preferential voting is that it requires a higher amount of knowledge amongst the electorate - always a dangerous assumption. I do however believe that people can rank their Green or UKIP preferences with a bit of practise).
One problem is the rules on how many candidates to rank. If you say ALL the candidates have to be ranked (like in Australia) you increase the spoilt ballot rate and 'donkey vote'(those going eeny meeny miny moe), whereas if you say people can rank as many or few as they like, you give a more powerful vote to those who know 'politics'. Unfortunately this tends to be the more wealthy. We could get into arguments about how voting per se favours the wealthy, but lets stick to STV.
Like FPTP, STV has a strong geographic link, but unlike FPTP that is not the ONLY thing that matters. Where you draw the boundaries can have a huge influence on the result under FPTP turning a narrow defeat into a landslide. This is less of a problem with STV, but it is still a problem. The degree of the problem depends on how proportional you decide STV should be. This depends on the number of MPs per constituency which determines the quota. This is where a brief description of how STV works is needed. You see, what the voters have to do is easy, the counting process however is another matter.
Firstly, it takes much longer to count preference vote systems (this also applies to the Alternative Vote but lets be honest, having to wait a few extra hours for a result is hardly a big problem). It takes longer because you might have to count the same ballot paper seven or eight times as 'surplus' votes of winners and losing candidates votes are re-allocated.
Basically pretty much every voter is guaranteed a vote that counts but this might not be their first preference, it might be their second, third or Nth preference depending on how many candidates there are. In each constituency, a pre-determined number of candidates are elected. You might decide five MPs is a good number for an area. This determines the 'quota' which would basically be the total number of votes divided by six (one more than the number to be elected), plus one vote - meaning a candidate would need around 17% of the votes to be elected. In practical terms, the quota does the same job as the 'threshold' does in a list PR system. It creates a barrier for smaller parties to get over for them to win any seats at all, so parliament is not overly fragmented. In list PR systems a reasonable threshold is usually judged to be around 4-5% as this limits parliament to no more than 8 or so parties represented.
In STV systems the quota threshold can be higher because we are not just counting first preferences, so for example, Greens are elected in Ireland despite their first preferences only reaching 5% because they pick up a lot of second and other preferences to take them over 17% in some areas.
Gerrymandering possibilities are more difficult under STV, but Ireland shows it can be done. One outrageous way available is to follow the Irish example of having 3 winners in some areas and 5 in others, this means the quota is different in different areas - an obvious way to alter the value of the vote. If you are to have an unequal voting system this is the way to go about it. But the boundaries like in FPTP are also a way of cheating. The fact that where you draw the boundaries is such an easy way to cheat in FPTP was one of the reasons I gave for it being semi-democratic and why it is the favourite system of dictators from Zimbabwe to Taiwan and this also remains a problem with STV, but less severe.
STV is however, fairer than FPTP to smaller parties who are not geographically concentrated and is more proportional. However it tends to be the third placed centre parties than benefit the most, which might explain why the Lib Dems like it so much.
One of the big disadvantages of STV that it shares with FPTP is how it under-represents women, minorities and lower socio-economic groups. This makes me very suspicious of STV. List PR tends to do wonders for women and lower socio-economic group representation and this is reflected in the fact that developed countries with list PR tend to have much lower inequality than similarly developed countries with FPTP or STV.
To conclude STV is better than FPTP, much better, but still has some serious deficiencies. It is not my ideal system, but I would knock on many doors if we the people were ever given an opportunity to choose it over FPTP.