Constructing the Number of Parties

@article{Dunleavy2003ConstructingTN,
  title={Constructing the Number of Parties},
  author={Patrick Dunleavy and Françoise Bouçek},
  journal={Party Politics},
  year={2003},
  volume={9},
  pages={291 - 315}
}
Forming an idea of the number of parties competing at elections or winning seats in legislatures is fundamental to disaggregated approaches to mapping party systems. We set out a method for systematically relating the behaviour of any `number of parties' index to the size of the largest party's vote and the numbers of parties in competition. This approach shows that the `effective number of parties' (N 2) can confuse real changes in party competition with mathematical quirks in the way that the… 

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