Majority bonus system

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A plurality or majority bonus system (MBS) is a mixed-member, partly-proportional electoral system that gives extra seats in a legislature to the party with a plurality or majority of seats. Typically, this is done with the aim of providing government stability, particularly in parliamentary systems.

The size of the majority bonus can vary substantially, and is usually a fixed number of seats, and may be conditional on the number of votes for each party. A relatively small majority bonus (such as in the reinforced proportionality system of Greece) may not always guarantee that a single party can form a government. A the same time, as the majority bonus is allocated in a non-compensatory manner, therefore if the majority bonus if as high as 50% and the largest party which has 50% of the popular vote receives it, this party may win as many as 75% of all seats. This differentiates it from the similar majority jackpot system.

It is currently used in Greece^[a] and on a local level in Italy and France.^{[citation needed]} In Argentina, it is used in the Chamber of Deputies of Santa Fe, Chubut, and Entre Ríos.^{[citation needed]}
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