The Additional Member System is a proportional representative electoral system
. It was devised for Germany
after World War Two
by the allies
and is now used in the UK
for the election
s of MSP
s for the Scottish Parliament
and for the members of the Welsh Assembly
. It is also used in New Zealand
also informs me that it is used in The Russian Federation
for their Parliamentary
Elections, more specifically the State Duma
or Gosudarstvennaya Duma. Thanks to the CIA World Factbook
for that one!
How it works
The country is divided into constituencies and regions (in Scotland they use the regions that are used for the European elections). Then when the voter votes he/she has two ballot papers, one for a constituency candidate and the other for a specific party.
The candidate vote is done via a simple plurality system (like the First Past the Post system used for British general elections). The candidate just needs to get one more vote than the previous candidate.
The specific party is chosen via the List system which is proportionally representative and is either a regional list or a national list.
Half the seats in the Parliament (or Assembly) are allocated to constituencies and are won by a candidate (single member constituencies) the other half are set aside for the list system. A party will get the same proportion of this latter half of seats as votes they got on the list system. So if a party got 12% of the vote in the list system then they will receive 12% of the seats allocated to the list system.
Scotland has the system as above. They have 129 Members of the Scottish Parliament with 73 single member constituencies and 8 regions with 7 candidates elected from each region. These regions are the European constituencies as of 1994.
Wales is slightly different. In Wales there is an Assembly which only has control of secondary legislation not primary legislation like Scotland. It also doesn't have any tax varying powers but a set sum from Whitehall instead. Also there are 20 members elected from each region and 4 additional members for each European constituency. There are 40 single member constituencies.
The Russian Federation
The Russian Federation only uses AMS for its Gosudarstvennaya Duma. This info is shamelessly cut and pasted from the CIA Factbook since I have no other sources for this.
"450 seats; 225 seats elected by proportional representation from party lists winning at least 5% of the vote, and 225 seats from single-member constituencies; members are elected by direct, popular vote to serve four-year terms"