Activist Model of Political Party Growth

TL;DR

This paper models the growth and decline of British political party memberships using epidemiological mathematics, highlighting the roles of activists and recruitment limits in shaping membership dynamics.

Contribution

It introduces the Limited Activist model, applying epidemiological concepts to political party membership, and demonstrates its effectiveness with historical data.

Findings

Parties experience cyclical membership growth and decline.

Activist recruitment is limited to a finite period, constraining growth.

Parties are not at risk of extinction but face fluctuating memberships.

Abstract

The membership of British political parties has a direct influence on their political effectiveness. This paper applies the mathematics of epidemiology to the analysis of the growth and decline of such memberships. The party members are divided into activists and inactive members, where all activists influence the quality of party recruitment, but only a subset of activists recruit and thus govern numerical growth. The activists recruit for only a limited period, which acts as a restriction on further party growth. This Limited Activist model is applied to post-war and recent memberships of the Labour, Scottish National and Conservative parties. The model reproduces data trends, and relates realistically to historical narratives. It is concluded that the political parties analysed are not in danger of extinction but experience repeated periods of growth and decline in membership, albeit at lower numbers than in the past.