Chapter 2: Theory of Consumer Behaviour

Summary

• The consumer's choice problem involves deciding how to spend income on goods to maximize satisfaction.
• Consumer preferences and affordability (income and prices) determine the best combination of goods.
• Two approaches to consumer behaviour: Cardinal Utility Analysis and Ordinal Utility Analysis.
• A consumption bundle consists of quantities of two goods (e.g., bananas and mangoes).
• Utility is the satisfaction derived from consuming goods, which varies among individuals.
• Key Concepts:
  • Total Utility (TU): Total satisfaction from consuming a quantity of a commodity.
  • Marginal Utility (MU): Change in total utility from consuming one additional unit.
• Demand is influenced by price, income, and preferences.
• The demand curve shows the relationship between quantity demanded and price, typically downward sloping.
• Normal Goods: Demand increases with income.
• Inferior Goods: Demand decreases as income increases.
• Substitutes: Goods that can replace each other (e.g., tea and coffee).
• Complements: Goods consumed together (e.g., tea and sugar).
• Changes in income, prices of related goods, or consumer preferences can shift the demand curve.

Chapter 2: Theory of Consumer Behaviour

Overview

Key Concepts

• Consumer Choice Problem: The consumer aims to maximize satisfaction based on preferences and affordability.
• Preferences: The likes of the consumer that influence their choices.
• Income and Prices: The consumer's ability to purchase goods is determined by their income and the prices of goods.

Approaches to Consumer Behaviour

1. Cardinal Utility Analysis: Assumes utility can be measured numerically.
2. Ordinal Utility Analysis: Focuses on the ranking of preferences without assigning numerical values.

Preliminary Notations and Assumptions

• Consumption Bundle: A combination of two goods, e.g., bananas (x₁) and mangoes (x₂).
• Utility: The satisfaction derived from consuming goods.
  • Total Utility (TU): Total satisfaction from consuming a quantity of a commodity.
  • Marginal Utility (MU): Change in total utility from consuming one additional unit.

Demand

• Demand Definition: The quantity of a commodity that a consumer is willing and able to purchase at various prices.
• Demand Curve: Represents the relationship between the quantity demanded and the price of a good.
• Law of Demand: As price decreases, quantity demanded increases, and vice versa.

Elasticity of Demand

• Price Elasticity of Demand: Percentage change in demand divided by the percentage change in price.
• Normal Goods: Demand increases with income.
• Inferior Goods: Demand decreases with income.

Budget Set and Budget Line

• Budget Set: All bundles of goods a consumer can buy with their income.
• Budget Line: Represents all bundles that cost the consumer their entire income; it is negatively sloping.

Indifference Curves

• Indifference Curve: A graph showing combinations of goods that provide the same level of satisfaction.
• Monotonic Preferences: Consumers prefer more of a good to less, leading to downward sloping indifference curves.

Shifts in Demand Curve

• Factors Causing Shifts:
  • Changes in income (rightward shift for normal goods, leftward for inferior goods).
  • Changes in prices of related goods (rightward shift for substitutes, leftward for complements).
  • Changes in consumer preferences.

Examples

• Example of Utility: A consumer derives different levels of utility from the same good based on personal preferences and circumstances.
• Example of Demand Curve: If the price of a good decreases, the quantity demanded increases, illustrating the law of demand.

Common Mistakes and Exam Tips

Common Pitfalls

• Misunderstanding Utility: Students often confuse total utility with marginal utility. Remember, total utility is the overall satisfaction from consuming a quantity, while marginal utility is the additional satisfaction from consuming one more unit.
• Ignoring Budget Constraints: Many forget to consider the budget line when determining the consumer's optimum bundle. Always check if the chosen bundle lies within the budget set.
• Confusing Normal and Inferior Goods: Students may mix up the definitions. A normal good's demand increases with income, while an inferior good's demand decreases as income rises.

Tips for Success

• Visualize Concepts: Use diagrams like indifference curves and budget lines to better understand consumer choices and preferences.
• Practice Elasticity Calculations: Familiarize yourself with how to calculate price elasticity of demand and understand its implications on total expenditure.
• Review Definitions: Ensure you can clearly define key terms such as 'substitutes', 'complements', 'monotonic preferences', and 'marginal rate of substitution'.
• Understand the Law of Demand: Remember that the demand curve is generally downward sloping due to the law of diminishing marginal utility.
• Work Through Examples: Apply concepts to real-world scenarios or practice problems to solidify your understanding.