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Simple Models: PPF & Supply/Demand Rebecca Tuttle Baldwin Bellevue Community College
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From the perspective of a society n Choices about linking inputs to outputs through production (allocation & distribution of mix of goods) n Three fundamental questions: What will be produced How will it be produced For whom
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What is possible? n Doesn’t mean it will be done but could be done n Can represent graphically or numerically n Each possibility gains something but we also face opportunity cost n Can illustrate with Production Possibilities Frontier (outermost curve, PPF)
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Shape of PPF tells us something n Linear or “bowed” n Constant or increasing rate of opportunity cost n Which is more “realistic”
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David Ricardo n Theory of Comparative Advantage – Not absolute advantage – Explanation for trade n Among nations n Exchange in markets between individuals
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Types of Economies n related but not the same as political structure n Differentiated by the way society answers those fundamental questions Command—centralized authority is decision- maker “laissez faire” or market economy has individual economic agents making choices mixed
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Focusing first on a market economy n Individual economic units as decision- makers n People in households n Firms in business sector n Interact in markets n Inputs through production functions to outputs (goods/services)
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What is a Market? n A market is the collection of buyers and sellers that, through their actual or potential interactions, determine the price of a product or set of products.
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Two types of goods n Consumer Goods—who uses? n Capital Goods—also an input! n Time Matters
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Market Outcome n Supply and demand interact through the price signal to reach equilibrium (market price and associated quantity where neither a surplus nor shortage exists).
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Exhibit 1a: The Demand Schedule for Milk
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Exhibit 1b: The Demand Curve for Milk
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Law of Demand All other things being equal (ceteris paribus), the lower the price, the higher the quantity buyers will wish to purchase in a given time period.
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Consumer Demand: Qd=f(P) n Taste/Preference n Income/Wealth n Price/availability of other goods n Expectations n Number of consumers
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Exhibit 2: An Increase in the Market Demand for Milk
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Exhibit 3a: The Supply Schedule for Milk
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Exhibit 3b: The Supply Curve for Milk
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Law of Supply As the price of a good rises, the quantity that firms are willing to supply will increase, c.p.
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Firms’ Supply: Qs=f(P) n Technology n Prices of other goods (factor prices) n Expectations n # of sellers
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Exhibit 4: An Increase in the Supply of Milk
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Equilibrium n Price at which QD=QS n Intersection of Supply & Demand n Market forces bring us to equilibrium when markets function n Point we stay at until “ceteris paribus” condition is violated for supply, demand, or both n no forces acting for change n not perfection
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Shortage n QD greater than QS n What has to happen to price to move us out of the shortage? n Laws of Supply & Demand tell us…as price increases, QD falls and QS increases…c.p. n Shortage=Excess Demand n No one coordinates
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Surplus n QS greater than QD n Also called Excess Supply n What has to happen to P to bring us to equilibrium? n Price has to fall
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Ceteris paribus n Latin phrase, meaning “all other things being equal” n key assumption for some of our micro theories/models
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Exhibit 5a: Equilibrium in the Milk Market (Market Schedules)
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Exhibit 5b: Equilibrium in the Milk Market (Market Curves)
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Price n Only piece of information individual agents on both side observe n Allocation mechanism/ rationing n what must be given in exchange for the good
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Do all markets reach equilibrium? n time n regulations (price ceiling/price floor) n what happens then?
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Effects of an Increase in Demand
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Effects of an Increase in Supply
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Indeterminate Effect of an Increase in Both Supply and Demand (Shift in Demand Dominates ) Indeterminate Effect of an Increase in Both Supply and Demand (Shift in Demand Dominates )
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Indeterminate Effect of an Increase in Both Supply and Demand (Shift in Supply Dominates) Indeterminate Effect of an Increase in Both Supply and Demand (Shift in Supply Dominates)
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Effects of Changes in Both Supply and Demand
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Effects of a Price Floor and Price Ceiling (Price Floor for Milk)
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Effects of a Price Floor and Price Ceiling (Price Ceiling for Rent)
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University lunchroom
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Americans’ tastes have shifted from beef to chicken n describe market for beef before & after that change n describe market for chicken n describe market for roadside hamburger stands
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For each of the following, decide whether shift or movement on what curve n The housing market: Consumers’ incomes fall n shift in demand, movement along supply n Sudden increase in price of milk, which is used to produce frozen yogurt. n supply shifts left, movement along demand
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Classic Example of Market--Competitive n Many buyers n Many sellers n Perfect Information n No barriers to entry or exit n Homogenous good
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Most markets are not the competitive ideal So market power exists-- ability to influence price
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The End!
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