Coalition Formation Game

The Game

How do party goals affect electoral competition and coalition formation?

• Work in groups: each group represents a party.
• Choose an ideological position, compete in an election, and negotiate a government.
• Your goal: maximize your own party’s points.

Preparation

1. Form 3–7 parties
2. Each party secretly draws a motive: office, policy, or both. Keep it secret until the final scoring stage.
3. At game setup, we select:
   • Possible voter distributions and the number of cabinet portfolios (5–10).
   • Whether opposition parties can receive policy points.
4. The app generates 1,000 voters on an ideological scale from 0 (left) to 100 (right).

The Election

1. Every party chooses a position between 0 and 100.
2. Voters choose the ideologically nearest party; ties are resolved randomly.
3. Votes are translated proportionally into 100 parliamentary seats.
4. The app displays the composition of parliament.

An absolute majority requires 51 seats.

Coalition Bargaining

• Formateur: The party with the most seats makes the first proposal.
• Parties respond in descending order of seat share and may make counterproposals.
• Negotiate four things:
  1. Which parties form the government.
  2. Which party gets the head of government.
  3. How the ministerial portfolios are allocated.
  4. The government’s agreed policy position (0–100).

How to Score

• Head of Governments grants 20 Points!
• Negative policy points are possible.
• Office points are available only to coalition parties.
• At setup, we decide whether opposition parties can earn policy points. If not, their policy component is zero.

Example: One Party, Three Motives

Party A is at position 30. The coalition agrees on 50. Party A holds 3 portfolios and the head of government.

• Office component: \(3\times10=30\).
• Policy component: \(60-|30-50|=40\).
• Head-of-government bonus: 20.