Parallel voting

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In political science, parallel voting or superposition refers to the use of two or more electoral systems to elect different members of a legislature. More precisely, an electoral system is a superposition if it is a mixture of at least two tiers, which do not interact with each other in any way; one part of a legislature is elected using one method, while another part is elected using a different method, with all voters participating in both. Thus, the final results can be found by calculating the results for each system separately based on the votes alone, then adding them together. A system is called fusion (no to be confused with electoral fusion) or majority bonus, another independent mixture of two system but without two tiers. Superposition (parallel voting) is also not the same as "coexistence", which when different districts in the same election use different systems. Superposition, fusion and coexistence are distinct from dependent mixed electoral systems like compensatory (corrective) and conditional systems.

Most often, parallel voting involves combining a winner-take-all system with party-list proportional representation (PR).^[1] While first-preference plurality with PR is the most common pairing in parallel voting, many other combinations are possible.

The proportion of list seats compared to total seats ranges widely; for example 30% in Taiwan, 37.5% in Japan and 68.7% in Armenia.^[2] Parallel voting is used in both national parliaments and local governments in Italy, Taiwan, Lithuania, Russia, Argentina, and other countries, making it among the world's most popular electoral systems.^{[citation needed]}