Additional member system

Additional member system

1. There are four electoral systems that broadly conform to the principle of proportional representation.

   • Single transferable vote
   • Alternative vote
   • Regional party list

2. AMS is used in the Scottish Parliament, the Welsh Assembly and the Greater London Assembly

   • Features
     • AMS is a 'mixed' system, made up of constituency and party-list elements
       • Electors cast two votes: one for a candidate in a constituency and the other for a party list election.
         • A proportion of the seats are filled by 'first-past-the-post', using single-member constituencies.
           • In Scotland and London, 56% of representatives are elected in this way. In Wales, this figure is 66%.
           • First past the post is NOT a type of proportional representation. Its a majortarian system.
         • The remaning seats are filled using a 'closed' party list system.
           • Parties are allocated seats in direct proportion to the votes they gain in each regional consituency. They fill these seats from their party list.
           • The party list element in AMS is used to 'top up' the constituency results. This is done 'correctively', using the D'Hondt method to achieve the most proportional overall outcome.
   • Advantages
     • The mixed character of this system balances the need for constituency representation against the need for electoral fairness.
       • Although the system is broadly proportional in terms of its outcomes, it keeps alive the possibility of single-party government
         • It allows voters to make wider and more considered choices. For example, they can vote for different parties in the constituency and list elections.
   • Disadvantages
     • The retention of single-member constituencies reduces the likihood of high levels of proportionality.
       • The system creates confusion by having two classess of representative.
         • Constituency representation will be less effective than it is in FPTP, because of the larger size of constituencies and because a proportion of representatives have no constituency duties.