I have recently written three posts on the vagaries and superlatives of first-past-the-post, the single-transferable-vote and list-PR. The purpose of which was not to give a comprehensive guide to these voting systems - wikipedia and the Electoral Reform Society carry out that task. No, what I wanted to do was to highlight what I think are the most important points that sometimes seem to get sidelined in the debate.
There are of course many other electoral systems in use and the theoretical possibilities are in fact infinite. It is a relatively new science that involves fairly basic mathematics so the layman has not so far been excluded.
I chose the three systems to outline that I did because I think they cover most of the realistic possibilities. I didn't have a specific post for the Alternative Vote - which is afterall the system we hopefully will soon get a referendum on, because basically it is the Single-Transferable-Vote but with just one member per constituency instead of 3,4,5 or 6 members.
In alphabetical order below I have put a summary of the three systems plus the Alternative Vote for those of you that want one line answers to how they work, the pros and cons etc.
Alternative Vote - No need to change boundaries, just allow people to put 1,2,3, instead of an X on the ballot. This preference system is used in Australia and does give fractionally more proportional results, although still expect one party rule on 35% of the vote and the 'wrong' winners to occur. Does nothing to help smaller parties get elected or represent minorities, women and the lower socio-class, although this preferential voting system does mean that you can show who really is your first preference without damaging your second, third preference etc. Suffers from most of the faults of first-past-the-post. Hopefully you will get a choice between this system and first-past-the-post in the next 18 months.
First-Past-The-Post - Used in UK and her ex-colonies. One member per constituency (an area drawn on the map to elect MP) or two or three members per ward (a smaller area for councillors) elected by putting an X or Xs on ballot depending on number of candidates to be elected.
This sounds great on first hearing. The candidate(s) with 'most' votes get elected and no one else gets a look in ('most' can be just 29% of vote or 18% of the electorate). This elected member is tied to one geographical area and 'represents' everyone within it.
This geographical link is paramount and overides EVERY other consideration including whether those elected truly are representative of their voters. A seemingly important flaw in my book, especially as it is impossible to draw boundaries fairly. If I was going to sum up the biggest con of this system it is this. Those who draw the boundaries have more power than those who actually vote. This is shown by the fact that the biggest 'change' elections (1945, 1966, 1983, 1997, 2010) come after significant boundary changes which generally occur every 12 years. All other discussion of this system is generally going to concentrate on the importance of boundaries. Generally the larger the boundary, the harder it is for smaller parties to be elected and the more unrepresentative and unaccountable the member elected. Roughly 75-85% of seats are safe - which means they do not change hands between boundary changes or even then maybe not ever!
List PR - Used by all the most democratic countries in the world on whatever index you like - equality, political engagement, least corrupt, prosperous, quality of public services. Purely proportional systems eliminates the importance of boundary drawing to the result. 'Nuff said!
Single-Transferable-Vote- Another British export to Ireland and Malta. Put 1,2,3 on ballot instead of X. Liked by ERS and Lib Dems. Favours third party and is less unfair to smaller parties. Complicated to count but not real problem which is that boundaries still influence result but much less so than first-past-the-post. Basically each constituency elects between 3-6 members and have to get over a quota of 25% of all preferences for 3 member constituencies and 17% for 6 member constituencies. Obviously the more members per constituency, the lower the quota and the more proportional and fairer the result. Not as proportional a system as List PR and still discriminates against smaller parties, women, minorities and lower socio-classes, but not as much as first-past-the-post does.