Electoral indexes

Basic electoral indexes

Effective Number of Parties [ENP]

ENPs - ENP acording to seats
ENPv - ENP acording to votes

Proportionality Index

competitiveness index

aggregation index

ENP

Markku Laakso and Rein Taagepera’s (1979) Effective Number of Parties Index using the formula:

Proportionality Index

The Proportionality Index used for research is based on Loosemore-Hanby Disproportionality Index (Loosemore, Hanby, 1971: 467-469) takes the formula:

Aggregation Index

To calculate the "ownership" of the most powerful electoral committee, use the Aggregation Index of Lawrence C. Mayer (1980), based on the formula:

Aggregation Index

The higher the value of the index, the more concentrated the party system (Banaś 2016: 53). The maximum value of the index (100) means the extreme concentration of the system by one party winning all the seats.

Competition Index

The Competition Index is calculated using the formula

Competition Index

The values of this index may vary within the range <0,1>. The lower the value, the lower the level of competitiveness within the system. The values no lower than 0,8 are generally perceived as a sign of high level of competitiveness (Antoszewski 2017).