Consumer Choice in Microeconomics

Consumer Choice in Microeconomics

  • Overview
    • Focuses on principles of consumer behavior in microeconomics.
    • Topics: Preferences, Utility, Budget Constraint, Constrained Consumer Choice.

Premises of Consumer Behavior

  • Individual Preferences
    • Determine the pleasure derived from goods/services.
    • Consumers maximize well-being under constraints.
  • Constraints
    • Limit real choices in consumption.
  • Objective of Microeconomics
    • Provide insights into consumer choices and decision-making models.

Properties of Consumer Preferences

1. Completeness

  • A consumer can rank choices:
    • Prefers Bundle 1 to Bundle 2, Bundle 2 to Bundle 1, or is indifferent.

2. Transitivity

  • If a consumer prefers Bundle A to B, and B to C, then A is preferred to C.

3. More Is Better

  • Consumers prefer more of a good or service, assuming all else is equal.
    • Example:
    • Good: More of a commodity is preferred (e.g. more pizzas).
    • Bad: Less is preferred (e.g. less pollution).

Preference Maps

  • Indifference Curve:
    • All bundles of goods equally desirable for the consumer.
  • Indifference Map:
    • Complete set of indifference curves showing preferences.
  • Key Properties:
    1. Bundles on curves further from the origin are preferred.
    2. Every possible bundle lies on indifference curves.
    3. Curves cannot cross.
    4. Curves slope downwards.

Willingness to Substitute Between Goods

  • Marginal Rate of Substitution (MRS):
    • Maximum amount of one good sacrificed to gain an additional unit of another.
    • MRS = -\frac{\Delta Z}{\Delta B} .
    • Negative slope indicates willingness to trade (sacrifice) goods.

Curvature of Indifference Curves

  • Most curves are convex to the origin, indicating diminishing marginal rate of substitution.
  • Special Cases:
    • Perfect Substitutes: Goods the consumer treats identically.
    • Perfect Complements: Goods consumed in fixed proportions (e.g., left and right shoes).

Utility

  • Utility:
    • Numerical values reflecting rankings of consumption bundles.
  • Utility Function:
    • U(Z, B) representing the utility derived from combinations of goods.

Ordinal vs Cardinal Preferences

  • Ordinal: Relative ranking without absolute comparisons (e.g., letter grades).
  • Cardinal: Absolute comparisons possible (e.g., money).

Marginal Utility and its Importance

  • Marginal Utility (MU):
    • Extra utility gained from consuming an additional unit of a good.
    • MU_Z = \frac{\Delta U}{\Delta Z} .

Relationship between Utility and MRS

  • MRS is the negative ratio of the marginal utilities of goods:
    MRSZ = -\frac{MUB}{MU_Z} .

Budget Constraint

  • Budget Line:
    • Represents bundles of goods affordable given prices and total income.
  • Equation:
    • pB B + pZ Z = Y , where pB and pZ are prices of burritos and pizzas, respectively.

Changes Affecting Constraints

  1. Price Changes:
    • If price of pizza doubles, budget line pivots (changes slope).
  2. Income Changes:
    • Increasing income shifts budget line outward without changing slope.

Constrained Consumer Choice

  • Optimal Bundle:
    • Consumption combination maximizing utility within budget.
    • At optimal point, the slope of the indifference curve equals the slope of the budget line (MRS = MRT).

Graphical Interpretation

  • Graphs show consumer preferences concerning pizzas and burritos.
    • Example: Point where budget line (consumption opportunity) touches indifference curve displays optimal choice.

Conclusion

  • Understanding consumer choice involves studying preferences, constraints, and utility.
  • Consumers make choices to maximize satisfaction based on available resources and market conditions.