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.
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.
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.
See also[edit | edit source]
References[edit | edit source]
- 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.
- Smith, WD. "Apportionment and rounding schemes".