In-Depth Notes on Microeconomics and Rational Economic Behavior

Overview of Economics

  • Economics studies mankind's ordinary business of life.
  • Examines individual and social actions related to the use of material requisites of well-being (Alfred Marshall).

Microeconomics

  • Studies choices made by individual decision-makers and the results of these decisions on economic conditions in various markets and industries.
  • Key decision-makers include:
    • Consumers
    • Producers
    • Employers
    • Workers
    • Lenders
    • Borrowers
Markets
  • Defined as institutions or arrangements bringing together buyers and sellers of goods/services.
  • Examples include:
    • Farmers’ market
    • Stock market
    • Job market
    • Used car market
Industries
  • Comprises firms producing identical or differentiated products (e.g., farms, car companies).

Big Microeconomic Assumption

  • Microeconomics operates under the assumption that individuals faced with scarcity make choices to achieve maximum satisfaction.
    • Three Components:
    1. Scarcity
    2. Choice
    3. Maximum Satisfaction
Scarcity
  • Defined as limited resources vs. unlimited wants.
  • Factors of Production include:
    • Land
    • Labor
    • Capital
    • Entrepreneurship
Economic Costs
  • All costs are viewed as benefits forgone.
  • Economic Cost Formula:
    Economic Cost=Explicit Cost+Implicit Cost\text{Economic Cost} = \text{Explicit Cost} + \text{Implicit Cost}
Types of Economic Costs

  1. Marginal Cost:

    • Cost of the next unit decision.
    • Includes explicit and implicit costs.
    • Example: Movie costs $15, with alternative time benefits forgone.

  2. Variable Cost:

    • Changes depending on the number of decisions (e.g., producing pizzas).
    • Example: Variable Cost for making 5 pizzas = $5 x 5 = $25.

  3. Fixed Cost:

    • Costs that do not vary with the level of activity (e.g., rent).
    • Example: Apartment rent, health insurance premiums.

  4. Sunk Cost:

    • Costs incurred in the past and cannot be recovered.
    • Example: Money paid for a truck rental last year.
Marginal Benefit
  • Increase in satisfaction from a decision, can be subjectively valued or monetary.
  • Defined as the willingness to pay for added benefit.
Avoided Costs and Marginal Benefit
  • Consider benefits of decisions related to avoided costs (e.g., using public transport).
Golden Rule of Rational Economic Behavior
  • Decision-making Principle:
    • Maintain activity level where (MB = MC).
    • Increase level of activity where (MB > MC).
    • Reduce level if (MB < MC).
Rational Economic Decision Making
  • Decisions depend solely on comparisons of marginal costs and benefits.
Incentives Matter
  • Decision-makers respond to changes in incentives, reflecting rational behavior.
Practical Application of Rational Economic Behavior
  • Examples: How many additional hours should a grocery store open after 5 PM?
  • Market dynamics can change the marginal benefit or marginal cost directly affecting decisions.
Conclusion
  • Understanding economics requires a clear grasp of core concepts like scarcity, choice, economic costs, and decision-making frameworks that guide rational behavior.