Oligopoly and game theory basics

Think of an oligopoly like a small group of best friends deciding where to go for lunch. There are only a few of them, and each friend's choice really affects where everyone else goes. If one friend says, "Let's get pizza!" everyone else has to think about whether they like pizza, if they want to go along, or if they'll suggest something else.

In the business world, an oligopoly is a market where:

• There are only a few large firms (companies) that dominate the entire industry.
• These firms sell products that are either identical (like oil) or similar but differentiated (like different brands of cereal).
• It's hard for new firms to enter the market (high barriers to entry), maybe because it costs a lot to start, or the existing companies have strong brand loyalty.
• The most important part: each firm's decisions (like changing prices or launching a new product) significantly affect the other firms, and they know it! This is called mutual interdependence.

Game theory is like the playbook these companies use. It's a way to study how people or companies make decisions when their success depends on the choices of others. It helps us predict what might happen when these few big companies interact.

Let's take the cell phone service industry in many countries. You probably have a few big names like Verizon, AT&T, or T-Mobile. These are classic oligopolies.

Imagine Verizon is thinking about lowering the price of its unlimited data plan. What do you think AT&T and T-Mobile will do? They can't just ignore it! If Verizon lowers its price, AT&T and T-Mobile might lose a lot of customers. So, they have to react. They might:

1. Lower their own prices to match Verizon.
2. Offer a better deal (like a free phone) to keep their customers.
3. Do nothing and hope their customers are loyal.

Verizon knows this! They know that if they cut prices, their rivals will probably cut prices too, leading to a "price war" where everyone makes less money. This strategic thinking, where each company anticipates the others' moves, is exactly what game theory helps us understand.

Let's break down how an oligopoly company might make a decision using game theory:

1. Identify the Players: First, the company figures out who the main competitors (rivals) are in the market. It's like knowing who is on the opposing team.
2. List Possible Actions: Next, the company lists all the different things it could do, like raise prices, lower prices, or start a new advertising campaign. These are its "moves."
3. Consider Rivals' Reactions: The company then tries to guess what each rival would do in response to each of its own possible actions. This is where mutual interdependence comes in.
4. Estimate Outcomes (Payoffs): For every combination of actions (what our company does AND what the rivals do), the company tries to figure out the result, like how much profit it would make. This is like scoring points in a game.
5. Choose the Best Strategy: Finally, the company picks the action that gives it the best outcome, considering what it expects its rivals to do. This is often aiming for a Nash Equilibrium, where no player can improve their outcome by changing their strategy, assuming other players' strategies remain unchanged.

Oligopolies can play the 'game' in different ways:

1. Collusion (Working Together): Sometimes, firms secretly agree to work together, like a team. They might agree to keep prices high or limit how much they produce to make more profit. This is called a cartel (like OPEC, the oil-producing countries), but it's usually illegal! Think of it like two friends secretly agreeing to both pick rock in rock-paper-scissors.
2. Price Leadership (One Big Boss): In some oligopolies, one big, powerful firm sets the price, and the others just follow along. It's like a lead singer in a band, and the other members play along. The smaller firms don't want to start a price war they can't win.
3. Non-Collusive (Everyone for Themselves): Most often, firms don't collude. They compete, but they still watch each other. This often leads to a kinked demand curve model, where if a firm raises its price, others don't follow (so it loses customers), but if it lowers its price, others do follow (so it doesn't gain many customers). It's like a standoff where nobody wants to make the first big move.

Here are some traps students fall into and how to dodge them:

• ❌ Mistake: Thinking oligopolies always collude (work together) or are always competitive like perfect competition. This is wrong because collusion is illegal and difficult to maintain, and they are definitely not like perfect competition. ✅ How to Avoid: Remember that oligopolies are unique because of mutual interdependence. They are in between monopolies and perfect competition. They can collude, but often they don't, and their decisions always depend on what rivals do.
• ❌ Mistake: Confusing an oligopoly with a monopoly (one seller) or monopolistic competition (many sellers of differentiated products). This is wrong because the number of firms is key. ✅ How to Avoid: Count the firms! Oligopoly = FEW big firms. Monopoly = ONE firm. Monopolistic Competition = MANY firms with slightly different products.
• ❌ Mistake: Forgetting that barriers to entry are important in oligopolies. This is wrong because without barriers, new firms would enter and it wouldn't be an oligopoly for long. ✅ How to Avoid: Always remember that it's hard for new companies to join an oligopoly market. This is what keeps the "few big players" in charge.
• ❌ Mistake: Not understanding the point of game theory. This is wrong because game theory isn't just about playing games; it's about strategic decision-making. ✅ How to Avoid: Think of game theory as a tool to predict how rational (smart) players (companies) will act when their choices affect each other. It's about anticipating moves and counter-moves.