competitiveness         Electoral Competitiveness
concentration           Electoral Concentration
enp                     Effective Number of Parties (ENP)
pns                     Party Nationalization Score (PNS)
psns                    Party System Nationalization Score (PSNS)
seats                   Allocating Seats by any method
seats_ha                Allocating Seats - Highest Averages
seats_lr                Allocating Seats - Largest Remainders
volatility              Electoral Volatility
