GAINS FROM TRADE:
- When economic interactions are voluntary, they generally benefit both participants.
- The buyer will pay a price up to her willingness to pay (WTP).
o WTP is determined by her income, prices of other goods and her preferences
(i.e. utility gain from the item relative to alternative uses of the money).
- The seller will accept a price as low as his willingness to accept (WTA).
o This is determined by the costs of providing the item, which in turn depends
on technology and the prices of inputs.
- A buyer and seller of an item can both benefit if the value of the item to the buyer is
more than the costs to the seller of supplying the item.
o WTP > WTA
- The difference WTP − WTA is the surplus created by the transaction and it measures
the gains from trade.
- How the surplus is divided between the seller and the buyer depends on the price
(P):
o Consumer surplus = WTP − P
o Producer surplus = P − WTA
- Surpluses can be regarded as rents, and they are an incentive to trade
o participants are better off compared to the reservation option (not trading)
- When surplus is positive,
o rational participants will choose to trade if a mutually beneficial price can be
agreed upon.
o trade would be a Pareto improvement.
o failing to exploit gains from trade would be inefficient.
WHAT ABOUT FAIRNESS?
Two issues arise:
- The gains to the buyer and the seller may be distributed unfairly
- Not everyone can have the same opportunity to benefit from trade in markets
o A person with no money/ resources cannot get gains from trade!
GAINS FROM TRADE
- In markets there can be many buyers and sellers
- Buyers may differ in their WTPs for different units
, CONSUMER SURPLUS:
- Demand curve (D) is willingness to pay (WTP)
- Consumer surplus (CS): obtained when a consumer pays
less than what he/she is willing to pay
(WTP > P)
- CS = WTP – P
- Total CS is sum of all the CS generated by all the cars
sold
- Consumer surplus: Area between demand curve and price
- (the shaded area)
- Consumer surplus = area of a triangle
½ x 32 x (8000 – 5440)
= $40 960
PRODUCER SURPLUS:
- A producer is willing to see a unit as long a the P at least
covers the cost of producing that unit (MC), so WTA = MC
- Producer surplus: the amount the producer receives over and
above WTA producer surplus contributed by a unit = P – MC
- E.g. if P = 3360, producer surplus of 20th car = 3360 – MC
= 1056
- Total PS is sum of PS generated from all units sold
- Producer surplus is the area above the MC curve and below the
price
- If P = 3360 and 42 cars are sold:
PS = ½ x 42 x (3360 – 1344)
= $42 336
GAINS FROM TRADE IN COMPETITIVE EQUILIBRIUM:
- Consider the perfectly competitive market for bread
- A competitive equilibrium allocation of bread has the property that total surplus is
maximized
- Total surplus (TS) = CS + PS
- Consumer surplus:
o Buyer’s WTP > price
CS = (€4.25 − €2.5) × 3 760 × ½
= €3 290
- Producer surplus:
o Seller’s MC <price
PS = (€2.5 − €1) × 3 760 × ½ = €2 820
- TS = €3 290 + €2 820 = €6 110
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller ambermcluckie. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $2.84. You're not tied to anything after your purchase.