Electoral competition

In political science, Duverger's law holds that in political systems with single-member districts and the plurality voting system,, two main parties tend to emerge. In this case, votes for minor parties can potentially be regarded splitting votes away from the most similar major party. In contrast, systems with proportional representation usually have more representation of minor parties in government.

Accountability, in terms of ethics and governance, is equated with answerability, culpability, liability, and the expectation of account-giving.

In economics and commerce, the Bertrand paradox — named after its creator, Joseph Bertrand — describes a situation in which two players (firms) reach a state of Nash equilibrium where both firms charge a price equal to marginal cost ("MC"). The paradox is that in models such as Cournot competition, an increase in the number of firms is associated with a convergence of prices to marginal costs. In these alternative models of oligopoly, a small number of firms earn positive profits by charging prices above cost. Suppose two firms, A and B, sell a homogeneous commodity, each with the same cost of production and distribution, so that customers choose the product solely on the basis of price. It follows that demand is infinitely price-elastic. Neither A nor B will set a higher price than the other because doing so would yield the entire market to their rival. If they set the same price, the companies will share both the market and profits.

Direct election is a system of choosing political officeholders in which the voters directly cast ballots for the persons or political party that they wanted to see elected. The method by which the winner or winners of a direct election are chosen depends upon the electoral system used. The most commonly used systems are the plurality system and the two-round system for single-winner elections, such as a presidential election, and proportional representation for the election of a legislature or executive.

The term "illiberal democracy" describes a governing system that hides its "nondemocratic practices behind formally democratic institutions and procedures". There is a lack of consensus among experts about the exact definition of illiberal democracy or whether it even exists.

Bertrand competition is a model of competition used in economics, named after Joseph Louis François Bertrand (1822–1900). It describes interactions among firms (sellers) that set prices and their customers (buyers) that choose quantities at the prices set. The model was formulated in 1883 by Bertrand in a review of Antoine Augustin Cournot's book Recherches sur les Principes Mathématiques de la Théorie des Richesses (1838) in which Cournot had put forward the Cournot model. Cournot's model argued that each firm should maximise its profit by selecting a quantity level and then adjusting price level to sell that quantity. The outcome of the model equilibrium involved firms pricing above marginal cost; hence, the competitive price. In his review, Bertrand argued that each firm should instead maximise its profits by selecting a price level that undercuts its competitors' prices, when their prices exceed marginal cost. The model was not formalized by Bertrand; however, the idea was developed into a mathematical model by Francis Ysidro Edgeworth in 1889.

Congressional stagnation is an American political theory that attempts to explain the high rate of incumbency re-election to the United States House of Representatives. In recent years this rate has been well over 90 per cent, with rarely more than 5–10 incumbents losing their House seats every election cycle. ^{The theory has existed since the 1970s, when political commentators were beginning to notice the trend, with political science author and professor David Mayhew first writing about the "vanishing marginals" theory in 1974.}

John E. Roemer is an American economist and political scientist. He is the Elizabeth S. and A. Varick Stout Professor of Political Science and Economics at Yale University. Before Yale, he was on the economics faculty at the University of California, Davis, and before entering academia Roemer worked for several years as a labor organizer. He is married to Natasha Roemer, with whom he has two daughters.

A Colonel Blotto game is a type of two-person constant-sum game in which the players (officers) are tasked to simultaneously distribute limited resources over several objects (battlefields). In the classic version of the game, the player devoting the most resources to a battlefield wins that battlefield, and the gain is equal to the total number of battlefields won.

The Roemer model of political competition is a game between political parties in which each party announces a multidimensional policy vector. Since Nash equilibria do not normally exist when the policy space is multidimensional, John Roemer introduced the concept of party-unanimity Nash equilibrium (PUNE), which can be considered an application of the concept of Nash equilibrium to political competition. It is also a generalization of the Wittman model of political competition.

A valence issue is a political issue where there is a broad amount of consensus among voters. As valence issues are representative of a goal or quality, voters use valence issues to evaluate a political party’s effectiveness in producing this particular goal or quality.

A hybrid regime is a type of political system often created as a result of an incomplete democratic transition from an authoritarian regime to a democratic one. Hybrid regimes are categorized as having a combination of autocratic features with democratic ones and can simultaneously hold political repressions and regular elections. Hybrid regimes are commonly found in developing countries with abundant natural resources such as petro-states. Although these regimes experience civil unrest, they may be relatively stable and tenacious for decades at a time. There has been a rise in hybrid regimes since the end of the Cold War.