Designing Electoral Districts for Proportional Representation Systems: How Electoral Geography and Partisan Politics Constrain Proportionality and Create Bias

An ecological inference approach to the origins of proportional representation

“…Rokkan’s proposition regarding ‘minority protection’ has been viewed as a precursor to the examination of partisan biases in electoral systems as the driving force for electoral reform (Calvo, 2009; Leemann and Mares, 2014). The distortion effects of majoritarian systems on party representation have their origins in the geographic dispersion of vote distributions, constituting a rationale for PR not necessarily tied to a socialist threat (Calvo, 2009; Rodden, 2009; Walter and Emmenegger, 2023). The end result may be often described as ‘majority protection’ and the perpetuation of partisan effects through electoral reform, rather than minority protection (Walter and Emmenegger, 2019).…”

“…Nevertheless, such uncertainty is likely not all-encompassing, otherwise we would observe only risk-averse decisions such as opting for very large districts – the safest option – and selecting the D’Hondt rule, a maximin approach for average parties (Fernández-de-Córdoba and Penadés, 2009). The tinkering with formulas and constituencies in districted electoral systems to systematically produce anticipated seat-to-vote distortions suggests that prospects often are well-informed (Walter and Emmenegger, 2019, 2023).…”