1. HL1 ECONOMICS MICROECONOMICS
An Introduction to Elasticity

2. ELASTICITY Price Elasticity of Demand (PED)
PED measures how sensitive the quantity demanded is to changes in the price.
You would expect the demand for most goods to fall as the price increases, but PED measures how much of a fall is likely.
It is important to distinguish between elastic and inelastic demand.

3. ELASTICITY Price Elasticity of Demand (PED)
Formula for PED: % change in quantity demanded % change in price How do we calculate the % change??? Change in Quantity Original Quantity ________________ (divided by) Change in Price Original Price

4. PED Example
The price of a popular chocolate bar increases from $3 to $4 per bar.
The quantity demanded per week falls from bars to 9000 bars.
Calculate the PED.
Change in Quantity = 1000
Original Quantity = __
= .3
Change in Price = = .3333
Original Price
What does this number mean ? – the product is inelastic.
What does inelastic mean? Read on!

5. ELASTICITY Price Elasticity of Demand (PED)
Elastic Demand
A small change in prices results in a relatively larger change in the quantity demanded.
Eg: If the price of a textbook increases by 10% and as result demands fall by 30%, demand is said to be elastic.
Demand is price elastic if the value calculated is more than 1. Therefore using our formula:
30 / 10 = 3

6. ELASTICITY Price Elasticity of Demand (PED)
Inelastic Demand
A relatively large change in price, led to a smaller change in the quantity demanded.
If the price of a product increases by 10% and demand only falls by 1%, then demand is said to be inelastic.
The same is of course true, for price drops, leading to a rise in demand.
Demand is inelastic if the figure calculated is less than 1. Therefore using our formula: 1/10 = .1
Our chocolate bar was an example of an inelastic good.

7. ELASTICITY Price Elasticity of Demand (PED)
Unitary Elasticity
If PED is exactly 1, this is know as unitary elasticity, which means that a change in price will lead to an identical change in quantity demanded.

8. ELASTICITY Price Elasticity of Demand (PED)
The Importance of PED for Business
It is useful for business to look at PED when deciding whether or not to change the price.
Revenue (price x quantity) will be affected by any change in price, but how it is affected depends on whether a product is elastic or inelastic.

9. ELASTICITY Price Elasticity of Demand (PED)
PED is Inelastic (less than 1) =
Business Can Increase Revenue by Increasing Price
They will lose some revenue from quantity demanded, but will gain more revenue from the higher prices, as demand changes less than proportionally to the change in price.

10. ELASTICITY Price Elasticity of Demand (PED)
PED is Elastic (Greater than 1) =
Businesses Can Increase Revenue by Lowering Prices
They will lose some revenue from the lower prices, but will gain more revenue from the higher quantity demanded, as demand changes more than proportionally to the change in price
This means that businesses must be careful to interpret their sales data correctly before making decisions on price changes.

11. PED EXERCISES (1)
American Airlines (AA) decides to increase its airfares on the New York to the US Virgin Islands (St Thomas) from $200 one way to $400 one way during the Christmas & New Year period. Weekly demands for the seats at this price level falls from per week to 9500 per week.
Calculate the Price Elasticity of Demand (PED)
Explain what the number means – are airfares on this route at this time elastic or inelastic??
From a revenue perspective was this a wise and smart decision for AA.

12. PED EXERCISE (2)
APPLE decides to decrease the selling price of its basic IPAD from $499 to $399. Weekly demand in a specific market increases from 10,000 units to 11,000 units.
Calculate the Price Elasticity of Demand
Explain what this number means
From a revenue perspective, was this a wise/ smart decision for APPLE.

13. ELASTICITY Income Elasticity of Demand (YED)
YED measures the change in demand for a product if there is a change in consumers income.

14. ELASTICITY Income Elasticity of Demand (YED)
Formula:
% Change in Quantity Demanded
% Change in Income
How do we calculate the % change???
Change in Quantity
Original Quantity
________________ (divided by)
Change in Income
Original Income

15. ELASTICITY Income Elasticity of Demand (YED)
Elastic Income Demand
If demand is more than proportionally affected by a change in income it is elastic.
If incomes rises by 5% and demand increases by 20% it clearly is elastic.
Income elastic goods are known as luxury goods.
Expense jewelry is a good example – demand will be significantly affected by changes in income.

16. ELASTICITY Income Elasticity of Demand (YED)
You would expect most goods to have a positive relationship to income with demand rising as income rises.
After all, if you have more money you will spend more. However, we need to distinguish between two different types of goods:
Normal Goods
Inferior Goods

17. ELASTICITY Income Elasticity of Demand (YED)
Normal Goods
Normal goods which will have a positive YED, because more is demanded as income rises – both the top and bottom of the calculation will have the same size.
Inferior Goods
Demand actually falls as income rises.
The best examples are the low cost value ranges stocked by most supermarkets.
As income rises, instead of customers buying more of these products, they may choose to swap to a higher quality or brand alternative.

18. ELASTICITY Income Elasticity of Demand (YED)
Inferior Goods
These products are extremely popular in times of recession and when incomes are falling, but are quickly abandoned once incomes and employment start to rise.
The success of low cost chains across Europe such as Lidl and Aldi will increase as the global economy tips into a recession.
As demand falls when income rises, the top and bottom of the equation will have different signs and therefore have a negative YED.

19. Income Elasticity of Demand (YED) Exercise
The average middle income salary increases from $50,000 to $70,000. The amount spent by these consumers on restaurant meals (fine dining) increases from $80 per week to $150.
Calculate the YED.
Explain the meaning of the number.
Are restaurant meals a normal or an inferior good? Why?

20. ELASTICITY Cross Elasticity of Demand (XED)
XED is a measure of responsiveness of change in the demand of one product to the change in the price of another (a complement or a substitute).

21. ELASTICITY Cross Elasticity of Demand (XED)
The formula is:
% Change in Quantity Demanded of Product A
% Change in the Price of Product B
How do we calculate the % change???
Change in Quantity A
Original Quantity A
________________ (divided by)
Change in Price of Product B
Original Price of Product B

22. ELASTICITY Cross Elasticity of Demand (XED)
Substitutes
Products that can replace each other (substitutes) will have a positive XED – the price of butter goes up, demand for margarine will increase as some people choose to swap to the option that has become relatively cheaper.

23. ELASTICITY Cross Elasticity of Demand (XED)
Complements
Products that are linked (complements) have a negative XED – as the price of airfares increases, the demand for hotels in resort locations may go down.

24. ELASTICITY Cross Elasticity of Demand (XED)
No Relationship Between Goods
Goods with no relationship will have an XED of zero – for example if the price of cars increases, demand for cheese will remain unchanged.

25. ELASTICITY Cross Elasticity of Demand (XED)
What does the number mean?
The higher the number calculated, the stronger relationship between the products, whether a complement or a substitute.
Examples
Coke and Pepsi are likely to have a very high, positive XED as they are very close substitutes.
Coke and Spirit will still have a positive XED, but it is likely to be lower, as Spirit is alternative soft drink, but not quite as close a match as another Cola.

26. Cross Elasticity of Demand (XED) Exercise
The number of subscribers to Super Cable increases from 10,000 per month in September to 11,000 per month in October. During October Direct TV decided to increase the cost of platinum TV package (all channels) from $60 per month to $80 per month.
Calculate XED
Explain the meaning of the number.