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Measurement and Interpretation of Elasticities. Chapter 5. Discussion Topics. Own price elasticity of demand Income elasticity of demand Cross price elasticity of demand Other general properties Applicability of demand elasticities. Key Concepts Covered….
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Discussion Topics • Own price elasticity of demand • Income elasticity of demand • Cross price elasticity of demand • Other general properties • Applicability of demand elasticities
Key Concepts Covered… • Own price elasticity = %Qbeeffor a given%Pbeef • Incomeelasticity = %Qbeeffor a given%Income • Cross priceelasticity = %Qbeeffor a given%Pchicken • Arc elasticity = range along the demand curve • Point elasticity = point on the demand curve • Price flexibility = reciprocal of own price elasticity
Own Price Elasticity of Demand Own price elasticity of demand Percentage change in quantity = Percentage change in price Arc Elasticity Approach Page 71
Own Price Elasticity of Demand Own price elasticity of demand Percentage change in quantity = Percentage change in price Arc elasticity Own price elasticity of demand Equation 5.3 = [QP] x [PQ] where: P= (Pa + Pb) 2; Q= (Qa + Qb) 2; Q = (Qa – Qb); and P = (Pa – Pb) The subscript “a” here again stands for “after” while “b” stands for “before” Page 71
Own Price Elasticity of Demand Own price elasticity of demand Percentage change in quantity = Percentage change in price The “bar” over the P and Q variables indicates an average or midpoint. Arc elasticity Own price elasticity of demand = [QP] x [PQ] where: P= (Pa + Pb) 2; Q= (Qa + Qb) 2; Q = (Qa – Qb); and P = (Pa – Pb) The subscript “a” here again stands for “after” while “b” stands for “before” Page 71
Own Price Elasticity of Demand Own price elasticity of demand Percentage change in quantity = Percentage change in price Specific range on curve Arc elasticity Pb Own price elasticity of demand Pa = [QP] x [PQ] Qb Qa where: P= (Pa + Pb) 2; Q= (Qa + Qb) 2; Q = (Qa – Qb); and P = (Pa – Pb) The subscript “a” here again stands for “after” while “b” stands for “before” Page 71
Demand Curves Come in a Variety of Shapes Perfectly inelastic Perfectly elastic Page 72
Demand Curves Come in a Variety of Shapes Inelastic Elastic
Demand Curves Come in a Variety of Shapes Elastic where %Q > % P Unitary Elastic where %Q = % P Inelastic where %Q < % P Page 73
Example of arc own-price elasticity of demand Unitary elasticity…a one for one exchange Page 73
Elastic demand Inelastic demand Page 73
Elastic Demand Curve Price c Pb Cut in price Brings about a larger increase in the quantity demanded Pa 0 Qb Qa Quantity
Elastic Demand Curve Price What happened to producer revenue? What happened to consumer surplus? c Pb Pa 0 Qb Qa Quantity
Elastic Demand Curve Price Producer revenue increases since %P is less that %Q. Revenue before the change was 0PbaQb. Revenue after the change was 0PabQa. c a Pb b Pa 0 Qb Qa Quantity
Elastic Demand Curve Price Producer revenue increases since %P is less that %Q. Revenue before the change was 0PbaQb. Revenue after the change was 0PabQa. c a Pb b Pa 0 Qb Qa Quantity
Elastic Demand Curve Price Producer revenue increases since %P is less that %Q. Revenue before the change was 0PbaQb. Revenue after the change was 0PabQa. c a Pb b Pa 0 Qb Qa Quantity
Revenue Implications Page 81
Elastic Demand Curve Price Consumer surplus before the price cut was area Pbca. c a Pb b Pa 0 Qb Qa Quantity
Elastic Demand Curve Price Consumer surplus after the price cut is Area Pacb. c a Pb b Pa 0 Qb Qa Quantity
Elastic Demand Curve Price So the gain in consumer surplus after the price cut is area PaPbab. c a Pb b Pa 0 Qb Qa Quantity
Inelastic Demand Curve Price Pb Cut in price Pa Brings about a smaller increase in the quantity demanded Qb Qa Quantity
Inelastic Demand Curve Price What happened to producer revenue? What happened to consumer surplus? Pb Pa Qb Qa Quantity
Inelastic Demand Curve Price a Producer revenue falls since %P is greater than %Q. Revenue before the change was 0PbaQb. Revenue after the change was 0PabQa. Pb b Pa 0 Qb Qa Quantity
Inelastic Demand Curve Price a Producer revenue falls since %P is greater than %Q. Revenue before the change was 0PbaQb. Revenue after the change was 0PabQa. Pb b Pa 0 Qb Qa Quantity
Inelastic Demand Curve Price a Consumer surplus increased by area PaPbab Pb b Pa 0 Qb Qa Quantity
Revenue Implications Page 81 Characteristic of agriculture
Retail Own Price Elasticities • Beef = -.6166 • Cheese = -.3319 • Bananas = -.4002 • Milk = -.2588 • Carrots = -.0388 Page 79
Interpretation Let’s take rice as an example, which has an own price elasticity of - 0.1467. This suggests that if the price of rice drops by 10%, for example, the quantity of rice demanded will only increase by 1.467%. P Rice producer Revenue? Consumer surplus? 10% drop 1.467% increase Q
Example • 1. The Dixie Chicken sells 1,500 Burger platters per month at $3.50 each. The own price elasticity for this platter is estimated to be –1.30. If the Chicken increases the price of the platter by 70 cents: • How many platters will the chicken sell?__________ • b. The Chicken’s revenue will change by $__________ • c. Consumers will be ____________ off as a result of this price change.
The answer… • 1. The Dixie Chicken sells 1,500 Burger platters per month at $3.50 each. The own price elasticity for this platter is estimated to be –1.30. If the Chicken increases the price of the platter by 70 cents: • How many platters will the chicken sell?__1,110____ • Solution: • -1.30 = %Q%P • -1.30= %Q[20%] • %Q=(-1.30 × 20) = –26% • So the new quantity of burger platters is 1,110, or • (1-.26) ×1,500, or .74 ×1,500
The answer… • 1. The Dixie Chicken sells 1,500 Burger platters per month at $3.50 each. The own price elasticity for this platter is estimated to be –1.30. If the Chicken increases the price of the platter by 70 cents: • How many platters will the chicken sell?__1,110____ • b. The Chicken’s revenue will change by $__-$588___ • Solution: • Current revenue = 1,500 × $3.50 = $5,250 per month • New revenue = 1,110 × $4.20 = $4,662 per month • So revenue decreases by $588 per month, or $4,662 • minus $5,250
The answer… • 1. The Dixie Chicken sells 1,500 Burger platters per month at $3.50 each. The own price elasticity for this platter is estimated to be –1.30. If the Chicken increases the price of the platter by 70 cents: • How many platters will the chicken sell?__1,110____ • b. The Chicken’s revenue will change by $__-$588___ • Consumers will be __worse___ off as a result of this price change. • Why? Because price increased.
Income Elasticity of Demand Income elasticity of demand Percentage change in quantity = Percentage change in income = [QI] x [IQ] where: I= (Ia + Ib) 2 Q= (Qa + Qb) 2 Q = (Qa – Qb) I = (Ia – Ib) Indicates potential changes or shifts in the demand curve as consumer income (I) changes…. Page 74
Some Examples Luxury good Elastic Inferior good Page 79
Example • Assume the government cuts taxes, thereby increasing disposable income by 5%. The income elasticity for chicken is .3645. • What impact would this tax cut have upon the demand for chicken? • Is chicken a normal good or an inferior good? Why?
The Answer • 1. Assume the government cuts taxes, thereby increasing disposable income (I) by 5%. The income elasticity for chicken is .3645. • What impact would this tax cut have upon the demand for chicken? • Solution: • .3645 = %QChicken % I • .3654 = %QChicken 5 • %QChicken = .3645 5 = + 1.8225%
The Answer • 1. Assume the government cuts taxes, thereby increasing disposable income by 5%. The income elasticity for chicken is .3645. • What impact would this tax cut have upon the demand for chicken? _____+ 1.8225%___ • Is chicken a normal good or an inferior good? Why? • Chicken is a normal good but not a luxury since the income elasticity is > 0 but < 1.0
Cross Price Elasticity of Demand Cross Price elasticity of demand Percentage change in quantity = Percentage change in another price = [QHPT] × [PTQH] where: PT= (PTa + PTb) 2 QH= (QHa + QHb) 2 QH = (QHa – QHb) PT = (PTa – PTb) Indicates potential changes or shifts in the demand curve as the price of other goods change… Page 75
Some Examples Values in red along the diagonal are own price elasticities… Page 80
Some Examples Values off the diagonal are all positive, indicating these products are substitutes as prices change… Page 80
Some Examples An increase in the price of Ragu Spaghetti Sauce has a bigger impact on Hunt’s Spaghetti Sauce than vice versa. Page 80
Some Examples A 10% increase in the price of Ragu Spaghetti Sauce increases the demand for Hunt’s Spaghetti Sauce by 5.349%….. Page 80