Additional member system

AMS vs. MMP

The term additional member system, as introduced by the Hansard Society, has been confused in the literature with the term mixed member proportionalrepresentation (in the broader sense) coined by New Zealand's Royal Commission on the Electoral System (1984–1986). The term AMS has been conflated also with parallel voting, which is not a compensatory system and in New Zealand was offered under the name supplementary member system. AMS has also been used to mean any system with additional members (both parallel voting and compensatory systems), therefore any two-tiered mixed system with first-past-the-post and additional list members. This is also why some unconventional systems, such as scorporo have also occasionally been described as 'additional member systems', although with compensatory systems this was also reinforced by the conflation of compensatory mixed systems and mixed-member proportional representation in general.