Informing Pricing and Resource Decisions

Market demand for a good at a particular price is the total Market demand of all consumers taken together. Understanding market demand is crucial for businesses and policymakers to make informed decisions about pricing, production, and resource allocation. It serves as a fundamental concept in economics and plays a vital role in shaping market dynamics.

Explanation of Market Demand for a Good: Calculating from Two Consumers to Graphical Derivation

• Two-Consumer Scenario: Aggregating Demand
  • Consider there are only 2 consumers in the market for a good ( figure ).
  • Suppose at price p′, the demand of consumer 1 is q’1 and that of consumer 2 is  q’2 . 
  • Then, the market demand for the good at p′ is  q’1 +   q’2. 
• Deriving Market Demand: Thus, the market demand for the good at each price can be derived by adding up the demands of the two consumers at that price
• Scaling Up to Handle Multiple Consumers: For more than two consumers, the market demand can be derived similarly. 
• Graphical Derivation: The market demand curve can also be graphically derived by horizontal summation.

Fig: Derivation of the Market Curve

Adding up Two Linear Demand Curves: Analyzing Consumer Curves for Market Demand

• Understanding d1(p) and d2(p) for Consumer 1 and Consumer 2:  In a market with two consumers, demand curves d1 (p) = 10 – p and d2 (p) = 15 – p.
• Price Threshold and Zero Demand: At prices greater than 10, consumer 1 demands 0 units of the good, while consumer 2 demands 0 units of goods.
• Deriving Market Demand: Market demand can be derived by adding these equations.

Elasticity of Demand: Analyzing Consumer Responsiveness to Price Shifts

• Responsiveness in Consumer Behavior: The Market demand for a good fluctuates in response to price changes, with some goods experiencing significant changes even with small price changes, while others remain unaffected by price changes.
• Defining Price Elasticity of Demand: Measure and Formula for Consumer Demand
  • Price elasticity of demand is a measure of the responsiveness of the demand for a good to change in its price. 
  • Price elasticity of demand for a good is defined as the percentage change in demand for the good divided by the percentage change in its price. 
  • The Price Elasticity Formula:
  • eD=(percentage change in demand for the good)/(percentage change in the price of the  good)

• Interpreting Elasticity Results: Assessing Consumer Responsiveness to Price Variations
  • Demand is Less Responsive Than Price: When the percentage change in quantity demanded is less than the percentage change in market price,
    • eD is estimated to be less than one and the demand for the good is said to be inelastic at that price.
    • Demand for essential goods is often found to be inelastic.(Figure)
  • Demand is More Responsive Than Price: When the percentage change in quantity demanded is more than the percentage change in market price, 
    • the market demand is said to be highly responsive to changes in market price and the estimated eD is more than one. 
    • The market demand for the goods is said to be elastic at that price.
• Demand for Luxury Goods: is seen to be highly responsive to changes in their market prices and eD>1.
• Unitary-Elastic Demand: The demand for a good is unitary-elastic when the change in quantity demanded equals the change in its market price. 

Elasticity along a Linear Demand Curve: Geometric Insights

The Price elasticity of demand is different at different points on the linear demand curve.

Geometric Measure of Elasticity along a Linear Demand Curve: Evaluating Elasticity

• The elasticity of a linear demand curve can easily be measured geometrically.
• The elasticity of Demand: At any point on a straight-line demand curve is given by the ratio of the lower segment and the upper segment of the demand curve at that point (figure).

Fig: Geometric Measure of Elasticity Curve

• Elasticity Across Different Points:
  • From the Horizontal to Vertical Axis: Elasticity is 0 at the point where the demand curve meets the horizontal axis and it is ∝ at the point where the demand curve meets the vertical axis. 
• Key Elasticity Points: At the midpoint of the demand curve, the elasticity is 1, 
  • At any point to the left of the midpoint, it is greater than 1 and
  • At any point to the right, it is less than 1.

Constant Elasticity Demand Curve: the Unitary Elastic Demand Curve

• Exploring Demand Curves: The elasticity of demand on different points on a linear demand curve is different, varying from 0 to ∞(figure). 
  • But sometimes, the demand curves can be such that the elasticity of demand remains constant throughout.

Fig: Constant Elasticity Demand Curve

• The Rectangular Hyperbola Demand Curve: The figure (c)  given above depicts a demand curve which has the shape of a rectangular hyperbola. 
• Unique Characteristics of a Constant Elasticity Demand Curve: This demand curve has a property that a percentage change in price along the demand curve always leads to an equal percentage change in quantity. 
  • Therefore, |eD | = 1 at every point on this demand curve. This demand curve is called the unitary elastic demand curve.

Factors Determining Price Elasticity of Demand for a Good: Nature, Necessities, and Substitutes

• Nature of Good: The price elasticity of demand for a good depends on its nature and the availability of close substitutes. 

• Inelastic vs. Elastic Demand: 

• • For instance, necessities like food are inelastic, while luxuries can be highly responsive to price changes. 
  • In contrast, food demand is generally price inelastic, while luxury demand is price elastic. 
• Close Substitutes and Elasticity:
  • Specific food items, like pulses, can be more elastic if close substitutes are easily available.
  • Inelastic demand is likely when close substitutes are not easily available, while elastic demand is when they are readily available.

Elasticity and Expenditure: Analyzing Price Changes and Goods

• The Expenditure on a Good: It is determined by its demand for goods multiplied by its price. 
• The price of a good and the demand for the good are inversely related to each other.
• The Change in Expenditure: It depends on the responsiveness of the good’s demand to price changes.
• Effects of Demand Responsiveness to Price Changes: If the percentage decline in quantity is less than the percentage increase in the price, the expenditure on the goods will go up.
• Price Increase Scenario: Consider an increase in the price of a good. 
  • If the percentage decline in quantity is greater than the percentage increase in the price, the expenditure on the goods will go down.
• Price Decrease Scenario: Consider a decline in the price of goods. 
  • If the percentage increase in quantity is greater than the percentage decline in the price, the expenditure on the goods will go up.
• Unchanged Expenditure: The expenditure on the good would remain unchanged if and only if the percentage change in quantity is equal to the percentage change in price, i.e., if the good is unit-elastic.