enp {politicsR}

The Effective Number of Parties Index

Description

'enp()' calculates the number of Effective Political Parties according to the formula proposed by Laakso and Taagepera (1979).

Usage

enp(x)

Arguments

x

(numeric). A numeric vector in the form of a proportion of votes or seats. The vector should between from 0 to 1.

Value

A value corresponding to the number of effective parties. Normally we deprecate the fraction in the analysis, leaving only the integer.

References

Laakso, M., & Taagepera, R. (1979). “Effective” Number of Parties: A Measure with Application to West Europe. Comparative Political Studies, 12(1), 3–27. https://doi.org/10.1177/001041407901200101

Examples

 enp(c(0.2, 0.3, 0.5))