Static population-monotonicity[1]: 147 , also called concordance[2]: 75 , says that a party with more votes should not receive a smaller apportionment of seats. Failures of concordance are often called electoral inversions or majority reversals.[3]
This phenomenon has been widely observed in elections in the UK, in which the first-past-the-post system has produced strange results, with huge gaps between the votes a party receives and the seats it recives. In the 2024 General Election, Reform UK won 14.3% of the popular vote (the third-highest share nationally) but only received 5 seats (0.7% of Parliament). Whilst, the Liberal Democrats won 12.2% of the vote—fewer than Reform UK—but won 72 seats.[4]
Examples of a full electoral inversion, the second-place party (in votes nationally) winning a majority of seats include the elections in Ghana in 2012, New Zealand in 1978 and 1981, and the United Kingdom in 1951.
References
- Balinski, Michel L.; Young, H. Peyton (1982). Fair Representation: Meeting the Ideal of One Man, One Vote. New Haven: Yale University Press. ISBN 0-300-02724-9.
- Pukelsheim, Friedrich (2017), "Divisor Methods of Apportionment: Divide and Round", in Pukelsheim, Friedrich (ed.), Proportional Representation: Apportionment Methods and Their Applications, Cham: Springer International Publishing, pp. 71–93, doi:10.1007/978-3-319-64707-4_4, ISBN 978-3-319-64707-4, retrieved 2021-09-01
- Miller, Nicholas R. (2012), "Election Inversions by the U.S. Electoral College", in Felsenthal, Dan S.; Machover, Moshé (eds.), Electoral Systems: Paradoxes, Assumptions, and Procedures, Berlin, Heidelberg: Springer, pp. 93–127, doi:10.1007/978-3-642-20441-8_4, ISBN 978-3-642-20441-8, retrieved 2024-07-13
- Baker, Carl; Pollock, Louie; Cracknell, Richard (2026-05-20). "General election 2024 results".
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