An overview of the main electoral voting systems around the world and how they work.
FIRST PAST THE POST
Constituency-based elections; winner is the candidate who gets the most votes
Pros: Gives a clear outcome, clear link between voter and elected representative
Cons: Every vote for the loser is wasted
Used: UK, US, India, Malaysia
SINGLE TRANSFERABLE VOTE
Multi-member constituency-based elections, where voters rank their candidate preferences with each preference counted and more than one candidate elected
Pros: Seen as the "purest" proportional representation system, ensuring that all votes count for something
Cons: Incredibly complicated to work out, and breaks the clear constituent-representative link
USED: Ireland, Scotland (in local government elections since 2007)
Similar to First Past The Post (FPTP), but here candidates need 50 per cent of the vote to get elected. If no-one gets this, the most unpopular candidate drops out, and their second preference votes are added on to those still in, until someone gets more than 50 per cent.
Pros: Retains constituency link, ends elections where MPs win with figures as low as 30 per cent of the vote, and eliminates the need for tactical voting
Cons: Critics say it isn't representative enough, and can sometimes be even worse than FPTP, locking in the dominance of the big parties
Used: Australia, Irish presidential elections, Fiji
ADDITIONAL MEMBER SYSTEM
A hybrid between FPTP and proportional representation. Members elected in a straight constituency fight are "topped-up" with others who win through a proportional representation system designed to compensate for the FPTP imbalances.
Pros: Best of both worlds, with constituency link still maintained, but a more proportional make-up in parliament
Cons: Creates a two-tier parliament of constituency and proportional representation members, and can lead to confusion among voters
Used: Scottish Parliament