Reproduced by permission of International IDEA from The International IDEA Handbook of Electoral System Design © International Institute for Democracy and Electoral Assistance 2002. The original work has been modified and we gratefully acknowledge it as the primary source of summarised material in this section, ‘Types of electoral systems’.

Electoral systems determine how votes cast at an election are translated into seats won by parties and candidates. Different electoral systems can produce different results, even from identical votes.

Compulsory voting in Australia originated in a private member’s Bill and was introduced under the Commonwealth Electoral Act 1924 after the fourth federal election and in NSW in 1928. About 32 countries have compulsory voting including about one-third of the Organisation for Economic Co-operation and Development (OECD) members as well as Egypt, Fiji, Peru, Singapore and Uruguay.

There are countless electoral system variations, but they can be grouped into three broad families:

• Majority systems
• Proportional representation systems
• Semi-proportional representation systems.