Study Notes on Perfect Competition

Definition of Perfect Competition
- Characterized by:
- A large number of firms.
- No barriers to entry.
- Firms have no competitive advantages. (e.g., no learning by doing, no brand loyalty)
- All firms and consumers have perfect information about prices.

Price Taking Concept
- Arises from the absence of market power.
- Example: Purchasing a common item (e.g., a bag of chips) at a grocery store:
- Unless buying the entire stock, consumers accept the market price (e.g., $2 for a bag of chips) without bargaining power.
- Sellers also act as price takers in the market:
- Unable to set prices above the market.
- If a firm attempts to raise its price, consumers will buy from competitors selling at market price (due to identical products).
- Firms cannot produce excess inventory since demand equals supply at the market price.

Definition of Economic Profit
- Economic Profit = Total Revenue - Economic Costs
- Economic Costs include:
- Explicit Costs (actual cash expenses)
- Implicit Costs (opportunity costs)
Behavior of Economic Profit under perfect competition:
- Explore implications on economic profits with free entry and exit.

Market vs. Individual Firm Decisions
- Market = collective actions of all producers and consumers
- Individual Firms respond to market conditions but make decisions based on their own context.

Firms are very small compared to market demand, facing a completely horizontal demand curve when acting as price takers.
Sales and Revenue Terminology:
- Marginal Revenue (MR): Additional revenue from selling one more unit.
- Average Revenue (AR): Total Revenue divided by quantity sold.
- Total Revenue (TR): Price times Quantity.

Definitions:
- Marginal Revenue is constant as firms operate in a competitive market.
- Graphs illustrate:
- Demand curve, Marginal Cost curve, and how they interact.
Revenue Calculations Table:
Quantity
Marginal Revenue
Average Revenue
Total Revenue
1
10
10
10
2
10
10
20
3
10
10
30
Fundamental characteristics include:
- MR = AR = Price
- Price is constant for all quantities sold (at equilibrium).

Quantity	Marginal Revenue	Average Revenue	Total Revenue
1	10	10	10
2	10	10	20
3	10	10	30

Firms aim to maximize profit where:
- Profit Maximizing Condition: $MR = MC$ (Marginal Revenue equals Marginal Cost)
- Effective Supply Curve intersects Effective Demand Curve at this point, determining optimal output level.

A typical marginal cost curve demonstrates:
- Initial decrease followed by eventual increases (law of diminishing returns).
- Use horizontal line as marginal revenue illustrating perfect competition.
Key Insight:
- Firms make decisions at the margin, producing additional units when marginal revenue exceeds marginal cost, benefiting from positive marginal profit.