A Baseline ABM of Party Competition

2017 ◽  
Author(s):  
Michael Laver ◽  
Ernest Sergenti
Keyword(s):  
Decision Rules ◽  
Party Competition ◽  
Baseline Model ◽  
Policy Positions ◽  
Agent Based ◽  
Party Leaders ◽  
Personal Ideal ◽  
Ideal Policy ◽  
Party Policy Positions ◽  
The Ideal

This chapter specifies the “baseline” agent-based model of dynamic multiparty competition, which derives from an article published by (Laver 2005). This assumes that each voter has in mind some personal ideal “package” of policy positions and supports the political party that offers the policy package closest to this. The dynamic system at the heart of the model is as follows: voters support their “closest” party in this sense; party leaders adapt the policy packages they offer in light of the revealed pattern of voter support; voters reconsider which party they support in light of the revealed pattern of party policy packages; and this process continues forever. This recursive model describes policy-based party competition as a complex system, and the baseline model specifies three decision rules that party leaders may deploy when they choose party policy positions in such a setting. These rules are Sticker (always keep the same position), Aggregator (move policy to the centroid of the ideal policy positions of your current supporters), and Hunter (if your last policy move increased your support, make another move in the same direction; or else change heading and move in a different direction).

Benchmarking the Baseline Model

2017 ◽  
Author(s):  
Michael Laver ◽  
Ernest Sergenti
Keyword(s):  
Policy Preferences ◽  
Policy Space ◽  
Baseline Model ◽  
Policy Positions ◽  
Voter Preferences ◽  
Optimal Representation ◽  
Ideal Points ◽  
The Dead ◽  
Party Policy Positions ◽  
The Ideal

This chapter begins the investigation of multiparty competition using the baseline model specified in Chapter 3 and methods and procedures specified in Chapter 4. The most significant results concern the representativeness of evolved configurations of party policy positions. In symmetric populations, the ideal points of voters are not best represented by a set of (Hunter) parties who compete for their support by trying to find popular policy positions. Instead, voter preferences are better represented by a set of (Aggregator) parties that do not compete with each other on policy at all but instead seek to represent the policy preferences only of their current supporters. This happens because the dynamics of vote-seeking competition in this setting cause parties to set policy positions closer to the center of the policy space than would be needed for optimal representation—while at the same time avoiding the dead center of the space.

Policy and the Dynamics of Political Competition

2005 ◽  
Vol 99 (2) ◽  
pp. 263-281 ◽  
Author(s):  
MICHAEL LAVER
Keyword(s):  
Party System ◽  
Political Competition ◽  
Decision Rules ◽  
Party Competition ◽  
Policy Position ◽  
Opinion Poll ◽  
Policy Positions ◽  
Agent Based ◽  
Series Of Experiments ◽  
Party Support

This paper proposes a model that takes the dynamic agent-based analysis of policy-driven party competition into a multiparty environment. In this, voters continually review party support and switch parties to increase their expectations; parties continually readapt policy positions to the shifting affiliations of voters. Different algorithms for party adaptation are explored, including “Aggregator” (adapt party policy to the ideal policy positions of party supporters), Hunter (repeat policy moves that were rewarded; otherwise make random moves), Predator (move party policy toward the policy position of the largest party), and “Sticker” (never change party policy). Strong trends in the behavior of parties using different methods of adaptation are explored. The model is then applied in a series of experiments to the dynamics of a real party system, described in a published opinion poll time series. This paper reports first steps toward endogenizing key features of the process, including the birth and death of parties, internal party decision rules, and voter ideal points.

Endogenous Parties, Interaction of Different Decision Rules

2017 ◽  
Author(s):  
Michael Laver ◽  
Ernest Sergenti
Keyword(s):  
Decision Rule ◽  
Decision Rules ◽  
Party Competition ◽  
Competitive Environment ◽  
Party Leaders ◽  
Robert Axelrod

This chapter attempts to develop more realistic and interesting models in which the set of competing parties is a completely endogenous output of the process of party competition. It also seeks to model party competition when different party leaders use different decision rules in the same setting by building on an approach pioneered in a different context by Robert Axelrod. This involves long-running computer “tournaments” that allow investigation of the performance and “robustness” of decision rules in an environment where any politician using any rule may encounter an opponent using either the same decision rule or some quite different rule. The chapter is most interested in how a decision rule performs against anything the competitive environment might throw against it, including agents using decision rules that are difficult to anticipate and/or comprehend.

Agree or disagree

2016 ◽  
Vol 23 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Zeynep Somer-Topcu
Keyword(s):  
Leadership Change ◽  
Party Leadership ◽  
Policy Positions ◽  
Party Leaders ◽  
Parliamentary Democracies ◽  
Party Positions ◽  
Leadership Changes ◽  
Using Data ◽  
The One ◽  
Party Policy Positions

Political party leaders are among the most influential actors in parliamentary democracies, and a change in party leadership is an important event for a party organization. Yet, we do not know how these leadership changes affect voter perceptions about party policy positions. On the one hand, we may expect party leadership changes to renew attention to the party, educate voters about its policy positions, and hence reduce disagreement among voters about party positions. On the other hand, rival parties may use a leadership change as an opportunity to defame the party, its leadership, and policies, and hence, increase voter confusion about the party’s policies. Using data from seven Western European democracies, I show that leadership changes help parties reduce voter disagreement about party policy positions. This effect is stronger if the new leader shifts the party’s policy positions.

scholarly journals Spatial models of political competition with endogenous political parties

2007 ◽  
Vol 362 (1485) ◽  
pp. 1711-1721 ◽  
Author(s):  
Michael Laver ◽  
Michel Schilperoord
Keyword(s):  
Political Parties ◽  
Political Competition ◽  
Spatial Models ◽  
Human Action ◽  
Party Competition ◽  
Party Leader ◽  
Agent Based ◽  
Party Leaders ◽  
Selection Processes ◽  
Policy Selection

Two important human action selection processes are the choice by citizens of parties to support in elections and the choice by party leaders of policy ‘packages’ offered to citizens in order to attract this support. Having reviewed approaches analysing these choices and the reasons for doing this using the methodology of agent-based modelling, we extend a recent agent-based model of party competition to treat the number and identity of political parties as an output of, rather than an input to, the process of party competition. Party birth is modelled as an endogenous change of agent type from citizen to party leader, which requires describing citizen dissatisfaction with the history of the system. Endogenous birth and death of parties transforms into a dynamic system even in an environment where all agents have otherwise non-responsive adaptive rules. A key parameter is the survival threshold, with lower thresholds leaving citizens on average less dissatisfied. Paradoxically, the adaptive rule most successful for party leaders in winning votes makes citizens on average less happy than under other policy-selection rules.

Modeling Multiparty Competition

2017 ◽  
Author(s):  
Michael Laver ◽  
Ernest Sergenti
Keyword(s):  
Decision Making ◽  
Adaptive Learning ◽  
Party System ◽  
Decision Rules ◽  
Agent Based Modeling ◽  
Party Competition ◽  
Strategic Analysis ◽  
New Approach ◽  
Agent Based ◽  
Autonomous Decision

This chapter begins with a brief discussion of the need for a new approach to modeling party competition. It then makes a case for the use of agent-based modeling to study multiparty competition in an evolving dynamic party system, given the analytical intractability of the decision-making environment, and the resulting need for real politicians to rely on informal decision rules. Agent-based models (ABMs) are “bottom-up” models that typically assume settings with a fairly large number of autonomous decision-making agents. Each agent uses some well-specified decision rule to choose actions, and there may be considerable diversity in the decision rules used by different agents. Given the analytical intractability of the decision-making environment, the decision rules that are specified and investigated in ABMs are typically based on adaptive learning rather than forward-looking strategic analysis, and agents are assumed to have bounded rather than perfect rationality. An overview of the subsequent chapters is also presented.

Nonpolicy Factors in Party Competition

2017 ◽  
Author(s):  
Michael Laver ◽  
Ernest Sergenti
Keyword(s):  
Party Competition ◽  
Policy Position ◽  
Policy Space ◽  
Political Candidates ◽  
Policy Positions ◽  
Lower Valence ◽  
Ideal Points ◽  
Party Policy Positions

Moving beyond the assumption that voters care about only the party policy positions on offer, this chapter models the possibility that they also care about perceived “nonpolicy” attributes of political candidates, such as competence, charisma, honesty. These characterize what have become known as “valence” models of party competition. Voters balance utility derived from each candidate's nonpolicy valence against utility derived from the candidate's policy position. The contribution of valence models has been to explain why all parties do not all converge on regions of the policy space with the highest densities of voter ideal points. Higher valence parties tend to go to regions of the policy space with higher voter densities, while lower valence parties are forced to steer well clear of these parties and pick policy positions in regions with lower voter densities.

The Informational Role of Party Leader Changes on Voter Perceptions of Party Positions

2017 ◽  
Vol 49 (3) ◽  
pp. 977-996 ◽  
Author(s):  
Pablo Fernandez-Vazquez ◽  
Zeynep Somer-Topcu
Keyword(s):  
Spatial Models ◽  
Party Competition ◽  
Party Leader ◽  
Necessary Condition ◽  
Policy Positions ◽  
Party Positions ◽  
European Parties ◽  
Citizen Perceptions ◽  
Party Policy Positions

According to spatial models of elections, citizen perceptions of party policy positions are a key determinant of voting choices. Yet recent scholarship from Europe suggests that voters do not adjust their perceptions according to what parties advocate in their campaigns. This article argues that voters develop a more accurate understanding of parties’ ideological positions following a leadership change because a new leader increases the credibility of party policy offerings. Focusing on Western European parties in the 1979–2012 period, it shows that having a new leader is a necessary condition for voters to more accurately perceive the left–right placements of opposition parties. Voters do not use party platforms to form perceptions of incumbent parties’ positions, regardless of whether the leader is new or veteran. These results have important implications for models of party competition and democratic representation.

scholarly journals The Politics of Fission: An Analysis of Faction Breakaways among Italian Parties (1946–2011)

2013 ◽  
Vol 45 (1) ◽  
pp. 121-139 ◽  
Author(s):  
Andrea Ceron
Keyword(s):  
Party System ◽  
Formal Model ◽  
Electoral System ◽  
Party Politics ◽  
Party Competition ◽  
Theoretic Model ◽  
Policy Positions ◽  
Party Leaders ◽  
Game Theoretic ◽  
Game Theoretic Model

This article investigates intra-party politics and explores the determinants of factional breakaways, going beyond the unitary actor assumption. It presents a game-theoretic model that focuses on intra-party competition and bargaining dynamics to analyse the interplay between party leaders and minority factions. It tests several hypotheses based on the formal model using a new dataset that contains information about the strength and policy positions of factions inside Italian parties, from 1946 to 2011, measured through quantitative content analysis of motions presented during party congresses. The results show that office, policy and electoral motives influence factions’ decisions to break away. Other elements – such as intra-party democracy, the electoral system and party system competitiveness – also affect leaders’ attitudes toward compromising and alter the likelihood of a split.

Party Leaders with Policy Preferences

2017 ◽  
Author(s):  
Michael Laver ◽  
Ernest Sergenti
Keyword(s):  
Dynamic Model ◽  
Decision Rules ◽  
Analytical Techniques ◽  
Agent Based Modeling ◽  
Vote Share ◽  
Policy Preferences ◽  
Agent Based ◽  
Party Leaders ◽  
Trade Offs

This chapter adapts the dynamic model of multiparty competition to take into account the possibility that party leaders take their own preferences into account when they set party policy. If they do this, they must make trade-offs between satisfying their private policy preferences and some other objective, whether this is maximizing party vote share or pleasing current party supporters. Models that specify such trade-offs have often been found intractable using traditional analytical techniques. However, they are straightforward to specify and analyze using computational agent-based modeling, though this does require a rethinking of the types of decision rules that party leaders might use. The chapter finds an analogue of the earlier finding that insatiable party leaders may win fewer votes than satiable leaders. Leaders who care only about their party's vote share may win fewer votes over the long haul than leaders who also care about their own policy preferences.

Sign in / Sign up

Export Citation Format

Share Document