ECON1101 Study Guide - Final Guide: Price Ceiling, Price Elasticity Of Demand, Economic Equilibrium
Elasticities
Price Controls
• Price controls - a gov. law or regulation that sets or limits the price to be charged for a
particular good.
• Price ceiling - a legal maximum on the price of a good, eg: rent control.
• For the price ceiling to bind and create shortage, it must be less than the equilibrium price.
• Dealing with persistent shortages:
• Causes rationing.
• Black markets develop.
• There could be a reduction in the quality of the good sold.
• Price ceilings may not end up helping people that the policy was designed to benefit.
• Price floor - a legal minimum on the price of a good, eg: minimum wage.
• Enacted with the goal of helping producers who are facing low market equilibrium prices.
• For floor price to bind and create surplus, it must be more than the equilibrium price.
• Dealing with persistent surpluses:
• If the minimum wage exceeds the equilibrium wage, the number of workers demanded at
that wage is less than the number of workers who are willing to work = surplus of
unemployed workers at the minimum wage.
• May not end up helping people that the policy was designed to benefit.
Elasticity
o Elasticity – how big or small the change in QD or QS is as a result of a price change.
Elasticity of Demand
• Price elasticity of demand – ((negative of the) % change in QD) divided by (% change in price).
• Since the QD is negatively related to the price, the elasticity of demand is a negative number.
• A given change in price has a larger impact on QD when the elasticity of demand is higher.
• A given shift of the supply curve will have a larger impact on equilibrium quantity (and a
smaller impact on equilibrium price) when the elasticity of demand is higher.
• Price elasticity of demand is a unit-free measure = provides a way to compare the price
sensitivity of demand of less expensive goods, like rice, with more expensive goods, like steak.
• Determinants of size of demand elasticity:
• Substitution possibilities - if a substitute is easily found, then the price elasticity will be high.
This depends on whether it is a necessity or a luxury.
• Budget share - if a good represents a large fraction of people's income, then the price
elasticity will be high.
• Temporary vs Permanent Price Change – demand is more elastic for temporary compared to
permanent price change.
• Time – demand tends to be more price sensitive over time.
Income Elasticity and Cross-Price Elasticity of Demand
• Cross-price elasticity of demand - % change QD of one good/% change in P of another good,
eg: an increase in P of rollerblades would increase QD of bicycles.
• For substitutes, E>0
• For compliments, E<0
Elasticity
Elasticity of Demand
“hape of Dead Curve
Perfectly inelastic
= 0
Vertical
Inelastic
< 1
Relatively steep
Unit elastic
= 1
Elastic
> 1
Relatively flat
Perfectly elastic
Infinite
Horizontal
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