Interesting. When is it different from the other formula? Jameson
2012/12/13 Ross Hyman <[email protected]> > Here is a physics alternative to the "effective number of parties" > formulas mentioned on the Wikipedia page: > http://en.wikipedia.org/wiki/Effective_number_of_parties > > Based on the concept of entropy, a sensible formula for the effective > number of parties = exp(-sum_i P_i log(P_i)) > > where P_i is the portion of the votes or portion of seats for party i. > sum_i P_i =1. > > It is sensible because for an election where n parties get 1/n of the vote > each and the rest of the parties get zero votes, the effective number of > parties from the entropy formula is n. > > > > > > ---- > Election-Methods mailing list - see http://electorama.com/em for list info >
---- Election-Methods mailing list - see http://electorama.com/em for list info
