Additional member system is a hybrid system of both majoritarian and
proportional elements.
Voters mark an "X" next to the candidate they would like to represent
their constituency (FPTP) and proportional representation where voters
elect candidates from several parties to represent them at a regional
level.
Advantages
At least one effective vote so votes less likely to be wasted
Extends voter choice
The number of votes a party gains is reflected on the amount of
seats they are given ( proportional represenation).
Eliminates safe seats -> may encourage some people to vote
Proportional representation allows smaller parties to gain seats and representation in parliament
Coalitions are more likely- this may be a benefit because coalitions
collide two parties therefore may be more representative
Avoids situation where few marginal seats control the whole result
Disadvantages
Voter confusion - more complex method of
allocating seats, takes a longer time to
calculate so longer waiting time
The system of allocating seats is complex and many will
not understand what is happening to their votes.
Proportional representation gives area more than one
representative ( this may lead to constituents being confused about
who their constituency MP's and regional MP's ) -------> weak MP and
constituent link
Coalition governments may be less stable than majority government- if the government disagree and
are divided over certain issues the government will fail
Smaller parties holding the balance of power between two larger parties
Extremist parties have more of a chance to gain seats then under FPTP
Accountability maybe lost in a coalition where the smaller party is dictating however the larger party takes responsibility
Unrepresentative political party activists deciding who goes on the list
Used in the Scottish parliament, Welsh assembly, greater London assembly
Some AMS systems use a threshold- (percentage of the vote a
party must gain to win any seats