Demand and the Demand Curve

DEMAND AND THE DEMAND CURVE

Introduction

  • Demand is defined as the willingness and ability of buyers to purchase different quantities of a good (product or service) at different prices during a specific time period.

The Law of Demand

  • The law of demand states:

    • As the price of a good rises, the quantity demanded falls.

    • As the price of a good falls, the quantity demanded rises.

    • This is observed under the condition of ceteris paribus (all other things being equal).

  • Graphical Representation:

    • The relationship between price and quantity is demonstrated on a Price-Quantity graph.

Ceteris Paribus

  • Definition:

    • A Latin term meaning “all other things constant” or “nothing else changes.”

  • Usage:

    • Ceteris paribus is utilized as an assumption to analyze the impact of one variable while keeping all other variables unchanged.

Quantity Demanded

  • Definition:

    • Quantity demanded refers to the number of units of a good that individuals are willing and able to buy at a specific price during a specified time period.

  • Distinction:

    • This concept of quantity demanded differs from demand, which encompasses the broader notion of willingness and ability of buyers to acquire varied quantities of a good at fluctuating prices.

Demand Schedule

  • Definition:

    • A demand schedule is a numerical tabulation that outlines the quantity demanded of a good at different price levels.

  • Example:

    • Price per Chocolate Box vs. Quantity Demanded:

    • $27 → 10 boxes

    • $24 → 13 boxes

    • $21 → 18 boxes

    • $18 → 25 boxes

    • $15 → 37 boxes

    • $12 → 58 boxes

    • $9 → 94 boxes

    • $6 → 162 boxes

    • $3 → 300 boxes

The Demand Curve

  • Definition:

    • The demand curve is a graphical representation that depicts the quantity of a product a household is willing to purchase at various price levels.

  • Structure:

    • The graph has prices plotted on the vertical axis and quantities demanded on the horizontal axis.

    • Each plotted point illustrates how many units of the good an individual will buy at that specific price.

    • The line connecting these points represents the demand curve.

Law of Demand and Slope of the Demand Curve

  • Relationship:

    • The law of demand indicates a negative or inverse relationship between price and quantity demanded, so demand curves slope downward.

Reasons for Decline in Quantity Demanded as Price Increases

  • Substitution Effect:

    • As prices rise, consumers may seek out cheaper alternatives.

  • Income Effect:

    • Increased prices reduce consumers' purchasing power, resulting in limited ability to buy the product.

  • Diminishing Marginal Utility:

    • As consumers acquire more units of a product, the additional satisfaction (utility) gained from extra units decreases, making them less inclined to pay higher prices.

Individual Demand Curve vs. Market Demand Curve

  • Individual Demand Curve:

    • Represents the price-quantity combinations for a single buyer (e.g., Jones's demand for chocolate bars).

  • Market Demand Curve:

    • Represents the aggregate price-quantity combinations for all buyers in the market, illustrating overall demand for a product (e.g., demand for chocolate bars among all buyers).

Market Definition

  • Market:

    • A market is defined as any setting where individuals come together to trade.

    • Trade can occur in either physical locations or virtual environments.

Derivation of Market Demand Schedule

  • Representation includes various buyers' demand for specific price levels:

    • Example table of Quantity Demanded based on different buyers (Jones and Smith).

Derivation of Market Demand Curve

  • Graphical representation that integrates individual demand curves into a single market demand curve, illustrating total demand across all buyers.

SHIFTS OF THE DEMAND CURVE

Increase in Demand

  • An increase in demand is shown as a rightward shift in the demand curve.

  • Example:

    • Demand Schedule A shifts to Demand Schedule B.

  • Price levels can increase quantity demanded at the same price levels.

Decrease in Demand

  • Conversely, a decrease in demand is indicated by a leftward shift in the demand curve.

  • Example:

    • Demand Schedule A shifts to Demand Schedule C.

Factors Causing Shifts in the Demand Curve

  • Income:

    • Normal Good: Demand rises as income rises; demand falls as income falls.

    • Examples: Caviar, designer goods.

    • Inferior Good: Demand falls as income rises; demand rises as income falls.

    • Examples: Instant noodles, used clothing.

    • Neutral Good: No change in demand as income changes.

  • Preferences:

    • Changes in consumer preferences can shift demand rightward (favoring a product) or leftward (disfavoring a product).

  • Prices of Related Goods:

    • Substitutes: Demand rises for one good when the price of a substitute rises.

    • Complements: Demand decreases for one good when the price of its complement rises.

  • Number of Buyers:

    • An increase in buyers (due to immigration or birth rate increases) raises demand; a decrease lowers demand.

  • Expectations of Future Prices:

    • Anticipating price increases may lead consumers to buy now, increasing current demand, and vice versa.

  • Government Regulations and Policies:

    • Subsidies: Lower effective prices increase demand.

    • Taxes: Raise effective prices and reduce demand.

    • Mandatory Requirements: Increase demand for certain goods.

    • Public Awareness Campaigns: Can enhance demand for targeted products.

MOVEMENT ALONG VS SHIFTS OF THE DEMAND CURVE

  • A change in demand exemplifies a shift in the entire demand curve.

  • Movement Along a Demand Curve:

    • Caused by changes in price leading to changes in quantity demanded without altering overall demand.

Summary of Change in Demand and Quantity Demanded

  • Change in Price:

    • Causes change in quantity demanded (movement along the curve).

  • Change in Determinants of Demand:

    • Causes a change in demand (shift of the curve).

COURSE REVIEW

Review Questions

  • What is the law of demand?

  • Which factors can shift the demand curve?

  • What is an inferior good? Provide an example.

  • Define substitutes and provide an example.

  • Define complements and provide an example.

  • Analyze the effects on the market for new cars based on government subsidies for buses and increasing consumer incomes (normal goods).

Exercise Question

  • Discuss the impact of technological advancements on the costs of smartphones, related apps, and fixed-line handsets.

Multiple-choice Questions

  1. What does the Law of Demand state?

    • Options: A) Increase in quantity demanded with price increase; B) Decrease in quantity demanded with price decrease; C) Decrease in quantity demanded with price increase; D) Increase in consumer income with price increase.

  2. What does 'quantity demanded' refer to?

    • Options: A) Total goods available; B) Willingness and ability to purchase at a specific price; C) Producer supply; D) Difference between supply and demand.

  3. What is a 'demand curve'?

    • Options: A) Demand changes over time; B) Consumer purchasing power illustrated; C) Relation of quantity demanded to income; D) Relation of price to quantity demanded.

  4. Characteristics of a normal good?

    • Options: A) Demand decreases as income increases; B) Demand increases as income increases; C) Unchanged demand regardless of income; D) Low demand due to poor quality.

  5. What defines an inferior good?

    • Options: A) Demand increases with income; B) Demand decreases with income; C) Inferior quality; D) Luxury item.

  6. Define a substitute:

    • Options: A) Used with another good; B) Can replace another good; C) Inferior quality; D) A complementary product.

  7. Define a complement:

    • Options: A) Replaces another product; B) Used together with another product; C) Inferior product; D) Luxury item.

  8. If an increase in the price of blue jeans increases the demand for tennis shoes, what is true?

    • Options: A) They are complements; B) They are inferior goods; C) They are normal goods; D) They are substitutes.

  9. What shifts the demand for watches to the right?

    • Options: A) Increase in price; B) Decrease in watch battery prices (if complements); C) Decrease in consumer income (if normal); D) Decrease in price of watches.

  10. Which does NOT shift the demand curve for good A?

    • Options: A) Price change of A; B) Price change of B (a complement); C) Price change of C (a substitute); D) Increase in average income.