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Wednesday, June 24, 2020

1.2.1 Price Elasticity of Demand (PED)


Syllabus Statement:

  • Explain the concept of price elasticity of demand, understanding that it involves responsiveness of quantity demanded to a change in price, along a given demand curve

  • State that the PED value is treated as if it were positive although its mathematical value is usually negative

  • Calculate PED between two designated points on a demand curve using the PED equation above

  • Explain, using diagrams and PED values, the concepts of price elastic demand, price inelastic demand, unit elastic demand, perfectly elastic demand and perfectly inelastic demand



PRICE ELASTICITY OF DEMAND (PED)

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PRICE ELASTICITY OF DEMAND (PED): Measures the responsiveness of the quantity demanded

of a good to a change in price

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  • Inelastic Demand ( 0 < | PED | < 1) : Quantity demanded is relatively unresponsive to price

  • Elastic Demand ( 1 < | PED | < ∞) : Quantity demanded is relatively responsive to price

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Formula:

  • As there is a Negative Causal Relationship between the price of a good and quantity demanded, the price elasticity of demand (PED) will always take a negative value:

  • For any percentage increase in price (a positive denominator), there follows a percentage decrease in quantity demanded (a negative numerator), thus resulting in a negative PED

  • Similarly, for any percentage decrease in price (a negative denominator), there follows a percentage increase in quantity demanded (a positive numerator), thus also resulting in a negative PED

  • However, to avoid confusion when making comparisons between different values of PED, the PED is treated as a positive value; hence, the absolute value of PED is obtained and evaluated

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Example: DVD Players

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    Suppose that in a department store, consumers buy 6000 DVD players at the original price of $255

    per unit. However, when the price is increased to $300 per unit, consumers buy 5000 DVD players.   

    Calculate the PED for DVD players in this department store.











    As the absolute value of PED is 0 < 0.94 < 1, the PED for DVD players is Elastic



TYPES OF PRICE ELASTICITY OF DEMAND (PED) 

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As the price elasticity of demand (PED) compares the percentage change in quantity demanded of a good to the percentage change in price, the PED can take a range of values with varying significance:








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SPECIAL CASES:


PRICE ELASTICITY OF DEMAND (PED) ALONG DEMAND CURVE

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The price elasticity of demand (PED) varies along any downward-sloping, straight-line demand curve:

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  • Demand is price elastic at high prices and low quantities

  • Demand is unitary price elastic at the midpoint of demand curve

  • Demand is price inelastic at low prices and high quantities

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Elastic Demand



  • At high prices and low quantities, the percentage change in quantity demanded is relatively large (as the denominator of 𝚫Qd / Q is small), while the percentage change in price is relatively small (as the denominator of 𝚫P / P is large)

  • Hence, the PED, given by a large percentage change in quantity demanded over a small percentage change in price, is greater than one (1 < PED < ∞), implying elastic demand

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Unitary Elastic Demand



  • At the midpoint of the demand curve, the percentage change in quantity demanded is equal to the percentage change in price

  • Hence, the PED, given by an equal percentage change in quantity demanded and price, is one, implying unitary elastic demand

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Inelastic Demand



  • At low prices and high quantities, the percentage change in quantity demanded is relatively small (as the denominator of 𝚫Qd / Q is large), while the percentage change in price is relatively large (as the denominator of 𝚫P / P is small)

  • Hence, the PED, given by a small percentage change in quantity demanded over a large percentage change in price, is less than one  (0 < PED < 1), implying inelastic demand

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NOTE: The terms ‘elastic’ and ‘inelastic’ should not be used to refer to an entire demand curve due to varying elasticity along the curve (with the exception of the three special cases where PED is constant: perfectly inelastic demand, unitary elastic demand, and perfectly elastic demand)




Syllabus Statement:

  • Explain the determinants of PED, including the number and closeness of substitutes, the degree of necessity, time and the proportion of income spent on food



DETERMINANTS OF PRICE ELASTICITY OF DEMAND (PED)

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DETERMINANTS OF PRICE ELASTICITY OF DEMAND: Factors that affect the elasticity of a good or service


1) NUMBER AND CLOSENESS OF SUBSTITUTES 

  • If a good has many close substitutes, consumers can easily switch to an alternative substitute if there is a change in price; hence, the demand for good will be price elastic

  • If a good has no close substitutes, consumers cannot switch to an alternative substitute if there is a change in price; hence, the demand for good will be price inelastic


2) DEGREE OF NECESSITY 

  • If a good is essential, it is categorized as necessities; hence, the demand for the good will be price inelastic as it needs to be consumed

  • If a good is non-essential, it is categorized as luxuries; hence, the demand for the good will be price elastic as it does not need to be consumed


3) TIME PERIOD

  • In a short time period, consumers have no time to consider the necessity of the good and find alternative substitutes; hence, the demand for the good will be price inelastic

  • In a long time period, consumers have more time to consider the necessity of the good and find alternative substitutes; hence, the demand for the good will be price elastic


4) PROPORTION OF INCOME

  • If the price of a good represents a small proportion of income, a change in price will have a smaller impact on the absolute amount of income spent; hence, the demand for the good will be price inelastic

  • If the price of a good represents a large proportion of income, a change in price will have a larger impact on the absolute amount of income spent; hence, the demand for the good will be price elastic




Syllabus Statement:

  • Examine the role of PED for firms in making decisions regarding price changes and their effect on total revenue



PRICE ELASTICITY OF DEMAND (PED) AND EFFECTS OF PRICE CHANGES ON TOTAL REVENUE

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TOTAL REVENUE (TR): Amount of money received by firms when they sell a good or service:

Total Revenue = Price x Quantity


The effect of a change in price on total revenue will depend on the price elasticity of demand (PED) of a good:

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  • Inelastic Demand ( 0 < PED < 1 ): Price and total revenue changes in the same direction

  • Unitary Elastic Demand ( PED = 1 ): Total revenue remains unchanged as price changes

  • Elastic Demand ( 1 < PED < ∞): Price and total revenue changes in opposite directions

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Hence, as the price elasticity of demand (PED) falls along a downward-sloping, straight line demand curve, total revenue is maximized when demand is unitary elastic:

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  • On the upper portion of the demand curve, where price is high and quantity demanded is low, demand is elastic; firms can therefore increase total revenue by lowering price

  • In this way, total revenue will increase as price falls, moving the firm along the demand curve until the midpoint where PED is unitary elastic

  • If prices fall below this midpoint, the total revenue will decrease as price is now in the inelastic portion of the demand curve

  • For this reason, firms maximize their total revenue at the midpoint of the demand curve where demand is unitary elastic - as total revenue remains unchanged as price changes



Table of Summary
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Inelastic Demand



  • When demand is inelastic, a decrease in price leads to a smaller percentage increase in quantity demanded; hence, the loss from the fall in price is larger than the gain from the quantity increase, resulting in an overall decrease in total revenue

  • When demand is inelastic, an increase in price leads to a larger percentage decrease in quantity demanded; hence, the gain from the rise in price is larger than the loss from the quantity decrease, resulting in an overall increase in total revenue

  • In other words, when demand is inelastic, price and total revenue changes in the same direction

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Unitary Elastic Demand



  • When demand is unitary elastic, a decrease in price leads to the same percentage increase in quantity demanded; hence, the loss from the fall in price is equal to the gain from the quantity increase, resulting in total revenue to remain unchanged

  • When demand is unitary elastic, an increase in price leads to the same percentage decrease in quantity demanded; hence, the gain from the rise in price is equal to the loss from the quantity decrease, resulting in total revenue to remain unchanged

  • In other words, when demand is unitary elastic, Total revenue remains unchanged as price changes

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Elastic Demand



  • When demand is elastic, a decrease in price leads to a larger percentage increase in quantity demanded; hence, the loss from the fall in price is smaller than the gain from the quantity increase, resulting in an overall increase in total revenue

  • When demand is elastic, an increase in price leads to a larger percentage decrease in quantity demanded; hence, the gain from the rise in price is smaller than the loss from the quantity decrease, resulting in an overall decrease in total revenue

  • In other words, when demand is elastic, price and total revenue changes in opposite directions




Syllabus Statement:

  • Explain why the PED for many primary commodities is relatively low and the PED for manufactured products is relatively high



PRICE ELASTICITY OF DEMAND (PED) OF PRIMARY COMMODITIES

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PRIMARY COMMODITIES: Goods arising directly from the use of natural resources or the factor of production ‘land’: this includes agricultural (food and non-edible products such as cotton), fishing, and forestry products, as well as products of extractive industries (oil, coal, and minerals)



The price elasticity of demand (PED) of primary commodities is relatively low:

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  • As primary commodities are necessities with no close substitutes, consumers cannot refuse to consume the good and cannot switch to an alternative substitute

  • For this reason, the demand for primary commodities is relatively unresponsive to price, with a change in price leading to a smaller percentage change in quantity demanded

  • Hence, the demand for primary commodities is price inelastic




PRICE ELASTICITY OF DEMAND (PED) OF MANUFACTURED PRODUCTS

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MANUFACTURED PRODUCTS: Processed goods arising from factors of production ‘capital’ and ‘labour’ using raw materials and intermediate inputs



The price elasticity of demand (PED) of manufactured products is relatively high:

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  • As manufactured products are often luxuries with many close substitutes, consumers can refuse to consume the good and can switch to an alternative substitute

  • For this reason, the demand for manufactured products is relatively responsive to price, with a change in price leading to a larger percentage change in quantity demanded

  • Hence, the demand for manufactured products is price elastic




Syllabus Statement:

  • Examine the significance of PED for government in relation to indirect taxes



PRICE ELASTICITY OF DEMAND (PED) AND INDIRECT TAXES

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INDIRECT TAX: Tax levied on the consumption of goods and services paid for by consumers

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  • The more inelastic the demand for the taxed good, the larger the tax revenue for the government

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  • In Figure (a) - showing a market with inelastic demand - and Figure (b) - showing a market with elastic demand - the initial market equilibrium is at Point A, determined by the intersection of the demand curve, D1, and supply curve, S1; hence, the equilibrium price and quantity is Pe and Qe respectively

  • Suppose the government introduces an indirect tax on every unit produced

  • As the cost per unit will increase by the tax per unit levied, production becomes less profitable; thus, firms will decrease supply, resulting in a leftward shift of the supply curve from S1 to S2 (vertical distance between S1 and S2 is equal to the per unit tax)

  • This change in supply forms a new after-tax market equilibrium at Point B, determined by the intersection of the demand curve, D1, and the new supply curve, S2; hence, the new equilibrium price increases to Pt, while equilibrium quantity decreases to Qt

  • As a tax revenue arises from an indirect tax, the shaded area represents the tax revenue collected and gained by the government ( Tax Revenue = Tax Per Unit x Quantity )

  • While tax revenue is generated by goods with both inelastic and elastic demand, the size of tax revenue varies between the two markets

  • In the case of inelastic demand, quantity demanded is relatively unresponsive to price: an increase in price (due to an indirect tax) leads to a smaller percentage decrease in quantity demanded, resulting in a large tax revenue

  • In the case of elastic demand, quantity demanded is relatively responsive to price: an increase in price (due to an indirect tax) leads to a larger percentage decrease in quantity demanded, resulting in a small tax revenue

  • For this reason, the overall tax revenue is larger when demand is inelastic; indirect taxes are therefore imposed on goods such as cigarettes and petrol which have low PED

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