Elasticity of Demand and Supply Flashcards
What is the relationship between P and Qd?
Negative. When P goes up Qd goes down. Law of demand.
How much does Qd go down when P goes up?
That depends.
For cigarettes if the price goes up what happens to the Qd?
It stays relatively the same. This is a necessity
What is price elasticity of demand?
A unit free measure that measures the responsiveness of Qd to a change in P.
How do you calculate PED?
%ΔQd/%ΔP
Is PED positive or negative and when?
It is always negative because when P is negative (i.e. when price goes down) Qd goes up so it is positive. When P is positive (i.e. price goes up) Qd is negative.
We thus ignore the negative sign as it will always be negative.
How do you calculate the %Δx?
(X2 - X1)/X2 x 100
ΔX/X2 x 100
So how do we really measure PED? Explain each step
(P2 - P1)/P2 x 100
Which you can simplify as
Qd2 - Qd1 P1
————— x ———
Qd1 P2 - P1
which is the same as
ΔQd P1
——- x ——
Qd1 ΔP
which is the same as
ΔQd P1
——- x ——
ΔP Qd1
So what is the final formula for PED?
ΔQd P1
——- x ——
ΔP Qd1
How many possibilities are there for the result of PED?
3
What are the possible results of PED?
- %ΔQd > %ΔP
- %ΔQd = %ΔP
- %ΔQd < %ΔP
When %ΔQd > %ΔP…
What is the PED?
D is elastic, i.e. Qd is very responsive to a change in P
PED > 1
When %ΔQd = %ΔP…
What is the PED?
D is unit elastic
PED = 1
When %ΔQd < %ΔP
What is the PED?
D is inelastic, i.e. Qd is not very responsive to a change in P
PED < 1
How do you calculate TR?
P x Q
When D is elastic what is your best move?
Decrease the price and total revenue will increase.
Why when D is elastic should you decrease the price?
Decreasing the price will increase the quantity demanded by more than the decrease in price and so the total revenue, being P x Q, will increase.
When D is inelastic what is your best move?
Increase the price and total revenue will increase
Why when D is inelastic should you increase the price?
Because the increase in price will not lead to a bigger decrease in price and total revenue will increase.
When D is unit elastic what is your best move?
Nothing, you have reached maximum TR.
When P is elastic what is the relationship between P and TR?
Negative. When you increase P lots of people leave the market so Q decreases and thus TR decreases.
When P is inelastic what is the relationship between P and TR?
Positive. When you increase P people will stay in the market because the good is a necessity and TR will increase.
Factors that will effect PED:
- Availability and closeness of substitutes
- Percentage of income spent on the good
- Luxury vs. necessity
- Addiction
- Advertisement
- The time period that has elapsed since the price change
How does the availability of substitutes effect PED and elasticity?
The more substitutes for a good the higher the PED and elasticity because if the price changes it is easier to find a replacement so you leave the market and Qd decreases.
The closer the substitutes for the good are to the good, the higher the PED and elasticity.