Chapter Five Choice. Economic Rationality u The principal behavioral postulate is that a decisionmaker chooses its most preferred alternative from those.

Slides:



Advertisements
Similar presentations
Chapter Six Demand. Properties of Demand Functions u Comparative statics analysis of ordinary demand functions -- the study of how ordinary demands x.
Advertisements

UTILITY MAXIMIZATION AND CHOICE
UTILITY MAXIMIZATION AND CHOICE
Preferences. Rationality in Economics u Behavioral Postulate: A decisionmaker always chooses its most preferred alternative from its set of available.
UTILITY MAXIMIZATION AND CHOICE
Chapter Twenty Cost Minimization.
Choice.
Chapter 3 Preferences Choose the “best” thing one can “afford” Start with consumption bundles (a complete list of the goods that is involved in consumer’s.
Properties of Demand Functions Comparative statics analysis of ordinary demand functions -- the study of how ordinary demands x 1 *(p 1,p 2,m) and x 2.
Chapter 4 Consumer Choice. © 2004 Pearson Addison-Wesley. All rights reserved4-2 Figure 4.1a Bundles of Pizzas and Burritos Lisa Might Consume.
Economic Rationality The principal behavioral postulate is that a decisionmaker chooses its most preferred alternative from those available to it. The.
Consumer Choice From utility to demand. Scarcity and constraints Economics is about making choices.  Everything has an opportunity cost (scarcity): You.
Chapter Five Choice. Economic Rationality u The principal behavioral postulate is that a decisionmaker chooses its most preferred alternative from those.
Chapter Three Preferences.
Chapter Five Choice. Economic Rationality u The principal behavioral postulate is that a decisionmaker chooses its most preferred alternative from those.
Chapter Three Preferences. Rationality in Economics u Behavioral Postulate: A decisionmaker always chooses its most preferred alternative from its set.
Choice. Q: What is the Optimal Choice? Budget constraint Indifference curves More preferred bundles.
Demand. Consumer Demand Consumer’s demand functions:
Choice Continued.
Chapter Five Choice.
Chapter Three Preferences. Rationality in Economics u Behavioral Postulate: An economic decisionmaker always chooses her most preferred alternative from.
Chapter Five Choice. Economic Rationality u The principal behavioral postulate is that a decisionmaker chooses its most preferred alternative from those.
Consumer Choice Theory Principles of Microeconomics 2023 Boris Nikolaev.
Chapter Five Choice 选择. Structure 5.1 The optimal choice of consumers 5.2 Consumer demand  Interior solution (内解)  Corner solution (角解)  “Kinky” solution.
Chapter 5 Choice.
© 2010 W. W. Norton & Company, Inc. 5 Choice. © 2010 W. W. Norton & Company, Inc. 2 Economic Rationality u The principal behavioral postulate is that.
Rational Choice. CHOICE 1. Scarcity (income constraint) 2. Tastes (indifference map/utility function)
1 Chapter 4 UTILITY MAXIMIZATION AND CHOICE Copyright ©2005 by South-Western, a division of Thomson Learning. All rights reserved.
Chapter 5 Choice of consumption.
Chapter Three Preferences. u Consumer behavior is best understood in three distinct steps: 1. Consumer Preferences: The first step is to find a practical.
Chapter 5 Choice Budget set + preference → choice Optimal choice: choose the best one can afford. Suppose the consumer chooses bundle A. A is optimal (A.
Budgetary and Other Constraints on Choice
Chapter 5 CHOICE.
L04 Choice. Big picture u Behavioral Postulate: A decisionmaker chooses its most preferred alternative from the set of affordable alternatives. u Budget.
CDAE Class 7 Sept. 18 Last class: Result of Quiz 1 2. Preferences and choice Today: 2. Preferences and choice Quiz 2 (Chapter 2) Next class: 3. Individual.
L02 Preferences. Rationality in Economics u Behavioral Postulate: A decisionmaker chooses its most preferred alternative from the set of affordable alternatives.
RL1 Review. u A decisionmaker chooses its most preferred alternative from the affordable ones. u Budget set u Preferences (Utility) u Choice (Demand)
L08 Buying and Selling. u Model of choice u We know preferences and we find demands u Q: Where does the mysterious income come from? u From selling goods.
Chapter 5 CHOICE.
Rational Consumer Choice Chapter 3. Rational Choice Theory Assumption that consumers enter the market place with clear preferences Price takers Consumers.
Course: Microeconomics Text: Varian’s Intermediate Microeconomics
L02 Preferences.
L06 Demand.
L08 Buying and Selling.
Chapter 5 Choice Key Concept: Optimal choice means a consumer chooses the best he can afford. Tangency is neither necessary nor sufficient. The correct.
L03 Utility.
Choice.
L03 Utility.
Chapter 5 Choice.
L08 Buying and Selling.
Chapter Three Preferences.
Rational Choice.
L08 Buying and Selling.
L06 Demand.
L02 Preferences.
L09 Review.
L04 Choice.
L02 Preferences.
Choice.
Chapter 3 Preferences.
L03 Utility.
5 Choice.
L08 Buying and Selling.
L02 Preferences.
L02 Preferences.
Molly W. Dahl Georgetown University Econ 101 – Spring 2009
L02 Preferences.
Economic Rationality The principal behavioral postulate is that a decisionmaker chooses its most preferred alternative from those available to it. The.
Presentation transcript:

Chapter Five Choice

Economic Rationality u The principal behavioral postulate is that a decisionmaker chooses its most preferred alternative from those available to it. u The available choices constitute the choice set. u How is the most preferred bundle in the choice set located?

Rational Constrained Choice x1x1 x2x2

x1x1 x2x2 Utility

Rational Constrained Choice Utility x2x2 x1x1

Rational Constrained Choice x1x1 x2x2 Utility

Rational Constrained Choice Utility x1x1 x2x2

Rational Constrained Choice Utility x1x1 x2x2

Rational Constrained Choice Utility x1x1 x2x2

Rational Constrained Choice Utility x1x1 x2x2

Rational Constrained Choice Utility x1x1 x2x2 Affordable, but not the most preferred affordable bundle.

Rational Constrained Choice x1x1 x2x2 Utility Affordable, but not the most preferred affordable bundle. The most preferred of the affordable bundles.

Rational Constrained Choice x1x1 x2x2 Utility

Rational Constrained Choice Utility x1x1 x2x2

Rational Constrained Choice Utility x1x1 x2x2

Rational Constrained Choice Utility x1x1 x2x2

Rational Constrained Choice x1x1 x2x2

x1x1 x2x2 Affordable bundles

Rational Constrained Choice x1x1 x2x2 Affordable bundles

Rational Constrained Choice x1x1 x2x2 Affordable bundles More preferred bundles

Rational Constrained Choice Affordable bundles x1x1 x2x2 More preferred bundles

Rational Constrained Choice x1x1 x2x2 x1*x1* x2*x2*

x1x1 x2x2 x1*x1* x2*x2* (x 1 *,x 2 *) is the most preferred affordable bundle.

Rational Constrained Choice u The most preferred affordable bundle is called the consumer’s ORDINARY DEMAND at the given prices and budget. u Ordinary demands will be denoted by x 1 *(p 1,p 2,m) and x 2 *(p 1,p 2,m).

Rational Constrained Choice u When x 1 * > 0 and x 2 * > 0 the demanded bundle is INTERIOR. u If buying (x 1 *,x 2 *) costs $m then the budget is exhausted.

Rational Constrained Choice x1x1 x2x2 x1*x1* x2*x2* (x 1 *,x 2 *) is interior. (x 1 *,x 2 *) exhausts the budget.

Rational Constrained Choice x1x1 x2x2 x1*x1* x2*x2* (x 1 *,x 2 *) is interior. (a) (x 1 *,x 2 *) exhausts the budget; p 1 x 1 * + p 2 x 2 * = m.

Rational Constrained Choice x1x1 x2x2 x1*x1* x2*x2* (x 1 *,x 2 *) is interior. (b) The slope of the indiff. curve at (x 1 *,x 2 *) equals the slope of the budget constraint.

Rational Constrained Choice u (x 1 *,x 2 *) satisfies two conditions: u (a) the budget is exhausted; p 1 x 1 * + p 2 x 2 * = m u (b) the slope of the budget constraint, -p 1 /p 2, and the slope of the indifference curve containing (x 1 *,x 2 *) are equal at (x 1 *,x 2 *).

Computing Ordinary Demands u How can this information be used to locate (x 1 *,x 2 *) for given p 1, p 2 and m?

Computing Ordinary Demands - a Cobb-Douglas Example. u Suppose that the consumer has Cobb-Douglas preferences.

Computing Ordinary Demands - a Cobb-Douglas Example. u Suppose that the consumer has Cobb-Douglas preferences. u Then

Computing Ordinary Demands - a Cobb-Douglas Example. u So the MRS is

Computing Ordinary Demands - a Cobb-Douglas Example. u So the MRS is u At (x 1 *,x 2 *), MRS = -p 1 /p 2 so

Computing Ordinary Demands - a Cobb-Douglas Example. u So the MRS is u At (x 1 *,x 2 *), MRS = -p 1 /p 2 so (A)

Computing Ordinary Demands - a Cobb-Douglas Example. u (x 1 *,x 2 *) also exhausts the budget so (B)

Computing Ordinary Demands - a Cobb-Douglas Example. u So now we know that (A) (B)

Computing Ordinary Demands - a Cobb-Douglas Example. u So now we know that (A) (B) Substitute

Computing Ordinary Demands - a Cobb-Douglas Example. u So now we know that (A) (B) Substitute and get This simplifies to ….

Computing Ordinary Demands - a Cobb-Douglas Example.

Substituting for x 1 * in then gives

Computing Ordinary Demands - a Cobb-Douglas Example. So we have discovered that the most preferred affordable bundle for a consumer with Cobb-Douglas preferences is

Computing Ordinary Demands - a Cobb-Douglas Example. x1x1 x2x2

Rational Constrained Choice u When x 1 * > 0 and x 2 * > 0 and (x 1 *,x 2 *) exhausts the budget, and indifference curves have no ‘kinks’, the ordinary demands are obtained by solving: u (a) p 1 x 1 * + p 2 x 2 * = y u (b) the slopes of the budget constraint, -p 1 /p 2, and of the indifference curve containing (x 1 *,x 2 *) are equal at (x 1 *,x 2 *).

Rational Constrained Choice u But what if x 1 * = 0? u Or if x 2 * = 0? u If either x 1 * = 0 or x 2 * = 0 then the ordinary demand (x 1 *,x 2 *) is at a corner solution to the problem of maximizing utility subject to a budget constraint.

Examples of Corner Solutions -- the Perfect Substitutes Case x1x1 x2x2 MRS = -1

Examples of Corner Solutions -- the Perfect Substitutes Case x1x1 x2x2 MRS = -1 Slope = -p 1 /p 2 with p 1 > p 2.

Examples of Corner Solutions -- the Perfect Substitutes Case x1x1 x2x2 MRS = -1 Slope = -p 1 /p 2 with p 1 > p 2.

Examples of Corner Solutions -- the Perfect Substitutes Case x1x1 x2x2 MRS = -1 Slope = -p 1 /p 2 with p 1 > p 2.

Examples of Corner Solutions -- the Perfect Substitutes Case x1x1 x2x2 MRS = -1 Slope = -p 1 /p 2 with p 1 < p 2.

Examples of Corner Solutions -- the Perfect Substitutes Case So when U(x 1,x 2 ) = x 1 + x 2, the most preferred affordable bundle is (x 1 *,x 2 *) where and if p 1 < p 2 if p 1 > p 2.

Examples of Corner Solutions -- the Perfect Substitutes Case x1x1 x2x2 MRS = -1 Slope = -p 1 /p 2 with p 1 = p 2.

Examples of Corner Solutions -- the Perfect Substitutes Case x1x1 x2x2 All the bundles in the constraint are equally the most preferred affordable when p 1 = p 2.

Examples of Corner Solutions -- the Non-Convex Preferences Case x1x1 x2x2 Better

Examples of Corner Solutions -- the Non-Convex Preferences Case x1x1 x2x2

x1x1 x2x2 Which is the most preferred affordable bundle?

Examples of Corner Solutions -- the Non-Convex Preferences Case x1x1 x2x2 The most preferred affordable bundle

Examples of Corner Solutions -- the Non-Convex Preferences Case x1x1 x2x2 The most preferred affordable bundle Notice that the “tangency solution” is not the most preferred affordable bundle.

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case x1x1 x2x2 U(x 1,x 2 ) = min{ax 1,x 2 } x 2 = ax 1

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case x1x1 x2x2 MRS = 0 U(x 1,x 2 ) = min{ax 1,x 2 } x 2 = ax 1

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case x1x1 x2x2 MRS = -  MRS = 0 U(x 1,x 2 ) = min{ax 1,x 2 } x 2 = ax 1

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case x1x1 x2x2 MRS = -  MRS = 0 MRS is undefined U(x 1,x 2 ) = min{ax 1,x 2 } x 2 = ax 1

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case x1x1 x2x2 U(x 1,x 2 ) = min{ax 1,x 2 } x 2 = ax 1

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case x1x1 x2x2 U(x 1,x 2 ) = min{ax 1,x 2 } x 2 = ax 1 Which is the most preferred affordable bundle?

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case x1x1 x2x2 U(x 1,x 2 ) = min{ax 1,x 2 } x 2 = ax 1 The most preferred affordable bundle

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case x1x1 x2x2 U(x 1,x 2 ) = min{ax 1,x 2 } x 2 = ax 1 x1*x1* x2*x2*

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case x1x1 x2x2 U(x 1,x 2 ) = min{ax 1,x 2 } x 2 = ax 1 x1*x1* x2*x2* (a) p 1 x 1 * + p 2 x 2 * = m

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case x1x1 x2x2 U(x 1,x 2 ) = min{ax 1,x 2 } x 2 = ax 1 x1*x1* x2*x2* (a) p 1 x 1 * + p 2 x 2 * = m (b) x 2 * = ax 1 *

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case (a) p 1 x 1 * + p 2 x 2 * = m; (b) x 2 * = ax 1 *.

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case (a) p 1 x 1 * + p 2 x 2 * = m; (b) x 2 * = ax 1 *. Substitution from (b) for x 2 * in (a) gives p 1 x 1 * + p 2 ax 1 * = m

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case (a) p 1 x 1 * + p 2 x 2 * = m; (b) x 2 * = ax 1 *. Substitution from (b) for x 2 * in (a) gives p 1 x 1 * + p 2 ax 1 * = m which gives

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case (a) p 1 x 1 * + p 2 x 2 * = m; (b) x 2 * = ax 1 *. Substitution from (b) for x 2 * in (a) gives p 1 x 1 * + p 2 ax 1 * = m which gives

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case (a) p 1 x 1 * + p 2 x 2 * = m; (b) x 2 * = ax 1 *. Substitution from (b) for x 2 * in (a) gives p 1 x 1 * + p 2 ax 1 * = m which gives A bundle of 1 commodity 1 unit and a commodity 2 units costs p 1 + ap 2 ; m/(p 1 + ap 2 ) such bundles are affordable.

Examples of ‘Kinky’ Solutions -- the Perfect Complements Case x1x1 x2x2 U(x 1,x 2 ) = min{ax 1,x 2 } x 2 = ax 1