Demand

Demand in Economics

Roadmap

  • Individual Demand: Understanding the demand of single consumers.

  • Market Demand: Aggregation of individual demands to form a market perspective.

  • Demand Shifts: Factors that cause the demand curve to shift.

Individual Demand

Learning About Individual Demand

  • Case Study: James

    • James contemplates buying Boba tea while walking to class.

    • He faces the decision: buy a Boba tea or save his money for other uses.

    • Price tag represents choices: "At this price, how much would I buy, if any?"

    • Survey Example: Asking James his expected purchases at varying prices:

    • $7: 1 tea

    • $6: 2 teas

    • $5: 3 teas

    • $4: 5 teas

    • $3: 7 teas

James’ Individual Demand Curve

  • Graphical Representation: Price on vertical axis and quantity demanded on the horizontal axis.

  • Definition: An individual demand curve shows how quantity demanded changes with price changes.

Analyzing Individual Demand Curve

  • Key Characteristics:

    • Downward-sloping curve: Indicates that lower prices lead to higher quantity demanded.

    • Intuitive understanding: Price decrease leads to increased desire for Boba tea as observed through other goods (e.g., jeans, books).

  • Nature of Demand Curve:

    • Represents a set of plans for purchases depending on price, holding other factors constant.

    • When other factors (costs, preferences) change, the demand curve shifts.

Law of Demand

  • Definition: The quantity demanded is inversely related to price; when prices decrease, quantity demanded increases.

Origin of Demand Curve

  • Rational Rule for Buyers: Consumers will buy more of a product if the marginal benefit is greater than or equal to the price.

  • Economic surplus is maximized when applying the Rational Rule, which reflects consumers’ decision-making.

  • Evaluating Purchase Decisions:

    • Assessing Marginal Benefit versus Marginal Cost following the Rational Rule.

    • Principles involved: Cost-Benefit Principle, Opportunity Cost Principle, Interdependence Principle.

Assessing Marginal Benefits

  • James's Decision-Making Process:

    • Marginal Benefit Analysis:

    • 1st Boba Tea: Maximum willingness to pay is $7.

    • 2nd Boba Tea: Willing to pay $6 due to social factor (meeting Chris).

    • 3rd Boba Tea: Valued at $5, considering flavor variety.

    • 4th Boba Tea: Valued at $4.5, considering opportunity cost of time.

Rationale Behind Downward Slope

  • Marginal Benefit Diminution:

    • Each additional unit provides lesser satisfaction, reflecting increasing opportunity costs and available alternatives.

  • Intuition: The first Boba has high satisfaction; subsequent ones diminish in immediate appeal, leading to higher opportunity costs influencing choice.

Demand in Relation to Marginal Benefits

  • Demand Curve Characteristics:

    • Example correlation: If price is $6, the demand is 2 Boba Teas; if price is $4, demand is 5 Boba Teas.

  • Marginal Benefit Concept:

    • Demand curve reflects the relationship between price and marginal benefit.

    • E.g., Marginal benefit of the second Boba is $6 and for the fifth Boba is $4.

Market Demand

Combining Individual Demands

  • Hypothetical Case: Adding James and Ali's individual demands.

    • At price $6:

    • James: 2 Boba teas

    • Ali: 2 Boba teas

    • Market Demand: 2 + 2 = 4 Boba teas.

    • At price $4:

    • James: 5 Boba teas

    • Ali: 6 Boba teas

    • Market Demand: 5 + 6 = 11 Boba teas.

Estimating Market Demand

  1. Survey Consumers: Gather data on quantities demanded at each price for a sample population.

  2. Aggregate Data: Total quantity needed to determine the market demand at each price was calculated.

  3. Scale Results: Adjust the total to represent the entire market.

  4. Graph Market Demand Curve: Visualizing total market demand at different prices.

Detailed Survey Example

  • Example table reflecting various consumer demands at different prices from several consumers (e.g., James, Ali, others).

Steps to Scale Market Demand

  • From survey results, the data is scaled up to capture a broader market perspective:

    • When price is $2, total demand = 1135.

    • When price is $3, total demand = 744.

    • Seventh column reflects scaling results to expected market share (e.g., multiplying by the total consumer base).

Plotting the Market Demand Curve

  • The market demand reflects collective consumer choices at pricing metrics.

    • Example: At price $6, demand projected at 69.9 million Boba teas per week.

The Law of Demand Applied to Market Demand

  • Definitions:

    • Intensive Margin: Price reductions lead to increased consumption among existing buyers.

    • Extensive Margin: Price decreases attract new buyers into the market.

    • Recognizing the significance of both margins for an accurate assessment of market demand behavior.

Case Studies for Margins

  • Intensive Margin: Price drop from $4 to $3 leads James to buy 2 more Boba.

  • Extensive Margin: Price drop from $7 to $6 leads Ali to buy Boba for the first time.

Changes Affecting Demand Curve

  • Price Effects: A price change moves along the curve; it does not shift it.

  • Shifts in demand occur based on external factors such as:

    1. Income Changes: Different effects on normal versus inferior goods.

    2. Tastes: Trends affecting demand for goods.

    3. Prices of Other Goods: Substitutes and complements influence demand dynamics.

    4. Expectations: Anticipated price changes influence present demand behaviors.

    5. Network Effects: Interactions among buyers affect perceived value.

    6. Changes in Buyer Population: New buyers can shift market demand significantly.

Income Effect

  • Normal Goods: Increased demand correlating with income rise.

  • Inferior Goods: Demand decreases as income rises; budget constraints dictate choices.

Tastes and Consumer Preferences

  • Advertising influences shifts in taste, promoting acceptance and increased demand for targeted goods.

Price of Other Goods

  • Substitutes: Demand increases when the price of a substitute rises.

  • Complements: Demand decreases when the price of a complementary good rises.

Expectations Impacting Demand

  • Choices affected by perceived future pricing compel consumers to alter immediate purchasing behavior.

Network and Congestion Effects

  • Network Effects: Increased utility as more consumers adopt a good (e.g., social networks).

  • Congestion Effects: Decreased utility with overcrowded resources (e.g., roads, public good usage).

Buyers: Population Effects on Demand

  • Market demand shifts based on the number and type of buyers – a crucial factor in understanding demand elasticity.

Practice Scenarios

Individual Demand for Cookies: Kate's Example

  • Explores marginal benefits ($5 for the first cookie, $4 for the second, etc.) against costs to determine purchasing decisions.

Market Demand for Cookies

  • Aggregates demand from multiple consumers to formulate market-level conclusions about demand at varying price points.

Scenario Analysis for Changes in Market Demand

  • Situational applications illustrating how individual movements or price adjustments affect demand visibility and adjustments.

Conclusion

  • This document serves as a thorough exploration of individual and market demand principles and implications, valuable for students and professionals in economics to understand underlying consumer behavior and market dynamics.