Population monotonicity: Difference between revisions

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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.<ref name="Balinski Young pp. 4602–4606">{{cite journal | last=Balinski | first=M. L. | last2=Young | first2=H. P. | title=A New Method for Congressional Apportionment | journal=Proceedings of the National Academy of Sciences | publisher=Proceedings of the National Academy of Sciences | volume=71 | issue=11 | date=1974-11-01 | issn=0027-8424 | doi=10.1073/pnas.71.11.4602 | pages=4602–4606}}</ref>
'''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 system|multi-winner methods]] in general. The term was first used by Balinski and Young in 1974.<ref name="Balinski Young pp. 4602–4606">{{cite journal | last=Balinski | first=M. L. | last2=Young | first2=H. P. | title=A New Method for Congressional Apportionment | journal=Proceedings of the National Academy of Sciences | publisher=Proceedings of the National Academy of Sciences | volume=71 | issue=11 | date=1974-11-01 | issn=0027-8424 | doi=10.1073/pnas.71.11.4602 | pages=4602–4606}}</ref>


The Population monotonicity criterion for an apportionment method is:
The population monotonicity criterion for a [[party list]] method is:

{{Definition| If the number of voters increases with fixed seats, no party delegation decreases.}}
{{Definition| If the number of voters increases then the party which the new voter endorsed cannot lose a seat.}}

By extension, the population 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.
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.<ref name=Smith>{{cite web |url=http://rangevoting.org/Apportion.html |title=Apportionment and rounding schemes |last=Smith |first=WD}}</ref>
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, every [[highest averages method]], including the current Huntington-Hill method, passes the criterion.<ref name=Smith>{{cite web |url=http://rangevoting.org/Apportion.html |title=Apportionment and rounding schemes |last=Smith |first=Warren D.}}</ref>


==See also==
==See also==
* [[Participation criterion]]
* [[Balinski–Young theorem]]
* [[Balinski–Young theorem]]
* [[Highest averages method]]
* [[Highest averages method]]
* [[House monotonicity criterion]]
* [[House monotonicity criterion]]

==References==

Latest revision as of 11:33, 30 April 2022

Population monotonicity is a feature of electoral systems. It is often stated as a criterion for party list methods, and by extension, for multi-winner 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 population 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, every highest averages method, including the current Huntington-Hill method, passes the criterion.[2]

See also

References

  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, Warren D. "Apportionment and rounding schemes".