Activist model of political party growth

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.

Modeling voting dynamics in a two-party system

“…While social interaction and word-of-mouth recruitment have been shown to account successfully for the growth of political parties in some contexts (see [21]), we hypothesize that mass media influence might be the driving force in the 2016 U.S. election in particular. One of the suggested methods for modeling media influence on voters' behaviors is TV exposure (see Zaller in [48]), which we use in combination with the TV mentions-by-candidate database in [77] and coverage studies in [64,65].…”

“…Thus, we can view voting as an epidemiological phenomenon, in the sense that individuals can infect others to act as they do, i.e., voting is contagious [33]. This approach has been applied to many areas outside of epidemiology, such as fanatic behavior [10] and, directly relevant to our discussion, political parties [21,40].…”

When behaviour turns contagious: the use of deterministic epidemiological models in modeling social contagion phenomena

“…Romero et al [54] assumed that third parties (political parties operating along with two major parties in a bipartisan system over a limited period of time) grow in a similar manner to epidemics in a population with the party faithful (activists) playing an extensive role in the growth of the party. Jeffs et al [55] in what was termed an "Activist Model of Political Party Growth" used a SIR model to examine the role of activists in the growth of a political party. Here 'S' represents those who do not belong to the political party (susceptibles), the party faithful (the members) are divided into recruiting activists 'I' who are "infectious" and recruit susceptibles by word of mouth, non-recruiting activists 'A' and inactive members 'M', both of whom play no part in the recruitment process.…”

Falling through the cracks: Modeling the formation of social category boundaries

“…Dynamical system models are useful for studying both formation and evolution processes because they enable tracking the feedback among many variables simultaneously. These models have been successful in explaining and predicting many complex social phenomena [ 24 ], such as the extinction of minority languages [ 25 ], the decline of religious affiliation [ 26 ], the polarization in the U.S. Congress [ 27 ], and changes in party memberships in the UK [ 28 ]. In this model, the process of creating social category boundaries is influenced by individual-level cognitive processes and social processes.…”