Om valkretsstorlekars spärreffekter
(Swedish)Manuscript (preprint) (Other (popular science, discussion, etc.))
In the absence of formal thresholds for representation, the constituency size will determine the effective threshold. In Swedish municipality elections there are (as of 2014) no formal thresholds, but the constituency sizes vary considerably. This note mainly presents the two mathematical formulas of interest for the calculation of effective thresholds. The voting share needed to get one seat under maximally charitable conditions (with respect to the distribution of votes among the other parties) is given by equation (7), where d is the first divisor (currently set to 1.4 in the Swedish system), M is the number of seats, and n is the number of parties. The voting share needed to be guaranteed to have one seat is given by equation (13). There is a threshold in between these extremes, a threshold at which there is a 50 % probability of winning one seat and a 50 % probability of winning none. For sufficiently large values of M, it is reasonable to believe that equation (5) provides a good approximation for the 50 % probability threshold.
election, threshold, constituency, apportionment, Swedish municipality elections, effective thresholds
valmetoder, representation, Sveriges valsystem, spärr, valkretsar, kommunalval, naturlig spärr
Political Science (excluding Public Administration Studies and Globalization Studies)
IdentifiersURN: urn:nbn:se:kth:diva-150702OAI: oai:DiVA.org:kth-150702DiVA: diva2:744572
QC 201409102014-09-082014-09-082014-09-12Bibliographically approved