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L05. Choice. Problem:. We know preferences (utility function) and We want to know optimal choice. Choice. $. $. $. $. $. $. $. $. $. $. Choice: geometric solution. x 2. x 1. Abstract approach. In the example we were given we found demands - two numbers
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L05 Choice
Problem: • We know preferences (utility function) and • We want to know optimal choice
Choice $ $ $ $ $ $ $ $ $ $
Abstract approach • In the example we were given we found demands - two numbers • Now we use abstract parameters • we find demand functionsNow we • 4 types of preferences
Abstract Cobb Douglass Function • Cobb Douglass utility functions and are equivalent in terms of preferences
Magic (Cobb-Douglass) formula Parameters:
Cobb-Douglas: Summary Utility function: or Solution: Shares of income
A) Let and B) Let and
Interiority Cobb – Douglass (always interior solution)
Perfect Complements (SOH) Interior or corner solution?
Is solution always interior? • Not necessarily • Even with well behaved preferences we might have a corner solution • Example: Perfect Substitutes
Perfect substitutes $ $ $ $ $ $ $ $ $ $
Perfect Substitutes x2 x1
Choice $ $ $ $ $ $ $ $ $ $
Is solution interior? • Hence demand and • Geometric interpretation • How to solve for corner solution? • Find a buddle using standard conditions • If some then in optimum
In Practice • Cobb-Douglass, Perfect Complements? • Quasilinear ? • Perfect Substitutes?