Cournot Competition vs Stackelberg Model
Cournot Competition and Stackelberg Model are two Market Structures concepts in AP Economics that students often mix up. Cournot competition is an oligopoly model where firms simultaneously choose how much quantity to produce, and the combined output sets the market price. The Stackelberg model is an oligopoly model where a leader firm sets output first and a follower firm then chooses its output in response. Here is how they compare side by side.
Each firm picks its output taking rivals' outputs as given, and equilibrium occurs where their reaction functions intersect (a Nash equilibrium in quantities). The result lies between monopoly and perfect competition: price exceeds marginal cost and firms earn positive profit, but less than a monopolist would. As the number of firms rises, the outcome approaches the competitive one.
Unlike Cournot's simultaneous choices, the Stackelberg leader moves first and, anticipating the follower's reaction, produces more than in Cournot to grab market share, earning higher profit. The follower produces less. Solved by backward induction, it gives the leader a first-mover advantage in quantity competition and produces a total output above the Cournot level (closer to competitive output).
Cournot vs Stackelberg: Moving at the Same Time or Moving First
| Cournot Competition | Stackelberg Model | |
|---|---|---|
| Order of moves | Both firms choose output at the same time | The leader chooses, then the follower responds |
| What the second firm knows | Only its rival's incentives, not its actual choice | The leader's output, already fixed and visible |
| How you solve it | Find where the two best response rules cross | Work backward, starting from the follower's best response |
| Equilibrium concept | Nash equilibrium in quantities | Subgame perfect equilibrium of a sequential game |
| Split of output between the firms | The two produce the same amount | The leader produces twice what the follower does |
| Industry output and price | Lower output, higher price | Higher output, lower price |
| Value of committing early | None, because there is no first move to make | Positive, but only if the follower believes it cannot be undone |
Moving first is worth money, and it comes out of the follower's pocket
Run both models on the same illustrative market. The price is 100 dollars minus one dollar for every unit the industry sells, and each firm makes a unit for 10 dollars, leaving a 90 dollar gap to divide. Under the simultaneous version, both firms land on 30 units. Industry output is 60, the price is 40 dollars, and each firm earns 30 dollars a unit on 30 units, or 900 dollars, so 1,800 dollars between them. Now let one firm choose first while the other watches. The leader knows the follower will supply half of whatever is left of the 90 dollar gap, so it produces 45 units and leaves 45 for the follower to halve. The follower's best answer is 22.5 units. Industry output is 67.5, the price falls to 32.5 dollars, and the margin is 22.5 dollars a unit. The leader collects 22.5 times 45, or 1,012.50 dollars, and the follower collects 22.5 times 22.5, or 506.25 dollars. Compare that with 900 dollars each: the leader is ahead by 112.50 dollars, the follower is behind by 393.75 dollars, and the two together lose 281.25 dollars. Buyers get 7.5 more units at a price 7.50 dollars lower.
The advantage only exists if the follower cannot ignore the first move
The leader's extra profit does not come from acting sooner on a calendar. It comes from making a choice the follower has to treat as settled. If the leader could quietly revise its output after seeing the follower's plan, the follower would ignore the announcement, and both would end up back at the simultaneous outcome with 30 units each. So the model is really about commitment: building capacity that would be wasted if unused, signing supply contracts, or making any move that would be expensive to reverse. Notice what the leader actually does with that commitment. It deliberately overproduces relative to its simultaneous choice, going to 45 units instead of 30, precisely because the follower will then pull back to 22.5. Producing more than you otherwise would, in order to change what someone else does, only makes sense when they are watching. That is also why the two models use different solution concepts. The simultaneous case asks for a /glossary/nash-equilibrium, where neither firm regrets its choice given the other's. The sequential case asks for a plan that is still sensible at every stage of the game, which is why you solve it backward from the follower's decision.
Frequently asked questions
What is the difference between the Cournot and Stackelberg models?
In Cournot competition both firms choose their output at the same time without seeing each other's decision, while in the Stackelberg model one firm chooses first and the other decides after observing that output. The timing changes the result: the Stackelberg leader produces more and earns more than a Cournot firm, and the follower produces less and earns less. Total industry output is higher and the market price is lower under Stackelberg.
Why does the Stackelberg leader produce more?
The leader produces more because it knows the follower will cut back in response, so expanding output does not trigger a matching expansion from the rival. In the standard setup the leader takes half the gap between the choke price and marginal cost, and the follower takes half of what remains, which is why the leader ends up with twice the follower's output. The strategy only works if the leader's output is a commitment it cannot quietly reverse.
Is total output higher under Stackelberg than under Cournot?
Yes, the sequential game produces more output and a lower price than the simultaneous one, so buyers are better off under Stackelberg. The leader gains less than the follower loses, so combined industry profit falls. That combination, more output at a lower price with smaller total profit, moves the market a step closer to the competitive result.
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