Population monotonicity

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Population monotonicity is a feature of electoral systems. It is often stated as a criterion for Party list methods, and by extension, for Multi-Member Systems methods in general. The term was first used by Balinski and Young in 1974.[1]

The Population monotonicity criterion for a Party list method is:

If the number of voters increases then the party which the new voter endorsed cannot lose a seat.

By extension, the house monotonicity criterion for a Multi-Member System is closely related to the Participation criterion

The population paradox is a counter-intuitive result of some procedures for apportionment. When two states have populations increasing at different rates, a small state with rapid growth can lose a legislative seat to a big state with slower growth.

Some of the earlier Congressional apportionment methods, such as the Hamilton method, could exhibit the population paradox. In 1900, Virginia lost a seat to Maine, even though Virginia's population was growing more rapidly. However, any type of Highest averages method such as the current method do not.[2]

See also[edit | edit source]

References[edit | edit source]

  1. Balinski, M. L.; Young, H. P. (1974-11-01). "A New Method for Congressional Apportionment". Proceedings of the National Academy of Sciences. Proceedings of the National Academy of Sciences. 71 (11): 4602–4606. doi:10.1073/pnas.71.11.4602. ISSN 0027-8424.
  2. Smith, WD. "Apportionment and rounding schemes".