Econ 101 - chp 4 Flashcards
Define the price elasticity of demand
is a unis free measure of the responsiveness of the quantity demanded of a good to a change in its price, ceteris paribus
a ratio of 2 percentage changes , measured in magnitude
What’s the formula to calculating the price elasticity of demand and how to calculate?
price elasticity of demand = (% change in quantity demanded)/ (% change in price)
we express the change in price as a percentage of the average price (point between original and new point) and the change in the quantity demanded as a percentage of the average quantity.
we express this number in terms of magnitude and it is a proportionate change
percentage change in price = (change in price/average price) x 100%
Why do we use the average price and quantity?
gives the most precise measurement of elasticity at the midpoint beween the original price + new price.
Define perfectly inelastic demand
when the quantity demanded remains constant when the price changes - the price elasticity of demand is zero
Define unit elastic demand
when the percentage change in the quantity demanded equals the percentage change int eh price - price elasticity of demand is 1.
Define inelastic demand
where price elasticity of demand is between zero and 1 - the % change in quantity demanded is less than the % change in the price
e.g. food + housing
define perfectly elastic demand
when the quantity demanded changes but an infinitely large percentage in response to a tiny price change - price elasticity of demand is infinity
the demand for a good that has a perfect substitute is perfectly elastic
e.g. soft drink
Define elastic demand
The price elasticity of demand is greater than 1
the percentage change in the quantity demanded exceed the percentage change in price
factors of elasticity of demand for a good
- closeness of substitutes
- proportion of income spend on the good
- time elapsed since the price change
How does the closeness of substitutes affect the elasticity of demand
the closer the substitutes for a good, the more elastic is the demand or it.
the degree of substitutability depends on how narrowly we define a good
luxury usually has many substitutes (elastic demand)
necessity (inelastic demand)
How does the proportion of income spend on the good affect elasticity of demand for a good?
ceteris paribus, the greater the proportion of income spent on a good the more elastic is the demand for it.
smaller proportion of your budget, that you barely notice the change so the demand is more inelastic
How doe sthe time elapsed since price change affect the elasticity for demand?
the longer the time that has elapsed since a price change, the more elastic is the demand.
time gives more substitutes developed, allowing the consumers to change their preferences and their demand
Is the elasticity of demand the same as the slope? why?
no - at the midpoint, the elasticity of demand is unit elastic while points above the midpoint are elastic and points below the midpoint are inelastic
Define the total revenue test
a method of estimating the price elasticity of demand by observing the change in total revenue that results from a change in the price, ceteris paribus
if a price cut increases the total revenue that means the elasticity fo demand is
elastic