Microeconomics: Production, Costs, and Market Structures – Study Notes

Chapter 6 – Production

Production Decisions

Production decisions in microeconomics involve determining how to combine inputs to produce outputs efficiently. Firms must consider technology, constraints, and input choices.

• Production Technology: The methods and processes used to transform inputs (labor, capital) into outputs.

• Input Decisions: Firms choose the optimal combination of inputs to minimize costs and maximize output.

• Production Function: Describes the relationship between inputs and output. For example: $Q = f(K, L)$ where $Q$ is output, $K$ is capital, and $L$ is labor.

Production Choices with One Variable Input

• Average Product (AP): Output per unit of a given input. $AP_L = \frac{Q}{L}$

• Marginal Product (MP): Additional output produced by an extra unit of input. $MP_L = \frac{\Delta Q}{\Delta L}$

Returns to Scale and Marginal Product

• Law of Diminishing Marginal Returns: As more of a variable input is added to fixed inputs, the additional output from each new unit of input eventually decreases.

• Isoquants: Curves showing all combinations of inputs that yield the same output.

• Marginal Rate of Technical Substitution (MRTS): The rate at which one input can be substituted for another while keeping output constant. $MRTS = -\frac{\Delta K}{\Delta L} = \frac{MP_L}{MP_K}$

Chapter 7 – Production Costs

Types of Costs

• Accounting Cost: Actual monetary outlays.

• Economic Cost: Accounting cost plus opportunity cost.

• Fixed Cost (FC): Costs that do not vary with output.

• Variable Cost (VC): Costs that change with output.

• Total Cost (TC): $TC = FC + VC$

• Average Cost (AC): $AC = \frac{TC}{Q}$

• Marginal Cost (MC): $MC = \frac{\Delta TC}{\Delta Q}$

Cost Minimization

• Firms choose input combinations to minimize cost for a given output.

• Occurs where the ratio of marginal products equals the ratio of input prices.

• Expansion Path: Shows cost-minimizing input combinations as output changes.

Economies and Diseconomies of Scale

• Economies of Scale: Long-run average cost decreases as output increases.

• Diseconomies of Scale: Long-run average cost increases as output increases.

Cost-Output Elasticity

• Measures the percent change in cost from a one-percent increase in output. $E_C = \frac{MC}{AC}$

Chapter 8 – Profits and Competitive Markets

Perfect Competition

In a perfectly competitive market, many firms sell identical products, and no single firm can influence the market price.

• Price Takers: Firms accept the market price as given.

• Homogeneity of Product: Products are identical across firms.

• Free Entry and Exit: Firms can enter or leave the market freely.

Profit

• Profit Equation: $\pi(Q) = R(Q) - TC(Q)$

• Marginal Revenue (MR): Change in revenue from selling one more unit.

• Optimal Output Rule: Produce where $MR = MC$

Short-Run Profit Maximization

• Produce where $MR = MC$ and $P \geq AVC$

• Shut down if $P < AVC$

Long-Run Equilibrium

• Firms enter or exit until economic profit is zero.

• Long-run supply is perfectly elastic if input prices are constant.

Chapter 9 – Competitive Market and Government Policy

• Consumer Surplus: Difference between willingness to pay and price paid.

• Producer Surplus: Difference between price received and minimum price willing to accept.

• Welfare Effects: Gains and losses to consumers and producers from changes in market policy.

• Price Controls: Government-imposed limits on prices (ceilings and floors).

• Trade Policy: Includes quotas and tariffs.

• Domestic Markets: Affected by taxes and subsidies.

Chapter 10 – Monopoly

Monopoly Profit Maximization

• Monopolist sets output where $MR = MC$

• Profit is maximized at this output and price.

• Rule of Thumb for Pricing: $P = \frac{\varepsilon}{1+\varepsilon} MC$ where $\varepsilon$ is the price elasticity of demand.

Multi-plant Monopoly

• Set $MR = MC_1 = MC_2$ for plants 1 and 2.

Sources of Monopoly Power

• Barriers to entry, product differentiation, and cost advantages.

Chapter 11 – Pricing with Market Power

Price Discrimination

• First-Degree: Charging each consumer their maximum willingness to pay.

• Second-Degree: Charging different prices for different quantities.

• Third-Degree: Charging different prices to different consumer groups. $MR_1 = MC$ and $MR_2 = MC$ for groups 1 and 2.

Chapter 12 – Monopolistic Competition and Oligopoly

Monopolistic Competition

• Many firms, differentiated products.

• Free entry and exit in the long run.

• Firms have some market power but face competition.

Oligopoly

• Few firms, interdependent decisions.

• Nash Equilibrium: Each firm chooses the best strategy given others' choices.

• Collusion: Firms cooperate to maximize joint profits (illegal in many countries).

• Prisoner's Dilemma: Illustrates why firms may not cooperate even when it is in their best interest.

Price Competition with Differentiated Products

• Firms set prices strategically, considering rivals' responses.