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The Challenges of Predicting Economic Behavior with the Calvo Modelby@keynesian
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The Challenges of Predicting Economic Behavior with the Calvo Model

by Keynesian TechnologyDecember 8th, 2024
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The first result establishes that the Calvo New Keynesian model is not continuously differentiable at ZINSS. This analytic proof highlights how constraints induce irregularities in the derivative, ruling out the use of the standard Grobman-Hartman theorem. However, away from aπ = 1, linearization can still serve as an approximation for local dynamics.
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Author:

(1) David Staines.

Abstract

1 Introduction

2 Mathematical Arguments

3 Outline and Preview

4 Calvo Framework and 4.1 Household’s Problem

4.2 Preferences

4.3 Household Equilibrium Conditions

4.4 Price-Setting Problem

4.5 Nominal Equilibrium Conditions

4.6 Real Equilibrium Conditions and 4.7 Shocks

4.8 Recursive Equilibrium

5 Existing Solutions

5.1 Singular Phillips Curve

5.2 Persistence and Policy Puzzles

5.3 Two Comparison Models

5.4 Lucas Critique

6 Stochastic Equilibrium and 6.1 Ergodic Theory and Random Dynamical Systems

6.2 Equilibrium Construction

6.3 Literature Comparison

6.4 Equilibrium Analysis

7 General Linearized Phillips Curve

7.1 Slope Coefficients

7.2 Error Coefficients

8 Existence Results and 8.1 Main Results

8.2 Key Proofs

8.3 Discussion

9 Bifurcation Analysis

9.1 Analytic Aspects

9.2 Algebraic Aspects (I) Singularities and Covers

9.3 Algebraic Aspects (II) Homology

9.4 Algebraic Aspects (III) Schemes

9.5 Wider Economic Interpretations

10 Econometric and Theoretical Implications and 10.1 Identification and Trade-offs

10.2 Econometric Duality

10.3 Coefficient Properties

10.4 Microeconomic Interpretation

11 Policy Rule

12 Conclusions and References


Appendices

A Proof of Theorem 2 and A.1 Proof of Part (i)

A.2 Behaviour of ∆

A.3 Proof Part (iii)

B Proofs from Section 4 and B.1 Individual Product Demand (4.2)

B.2 Flexible Price Equilibrium and ZINSS (4.4)

B.3 Price Dispersion (4.5)

B.4 Cost Minimization (4.6) and (10.4)

B.5 Consolidation (4.8)

C Proofs from Section 5, and C.1 Puzzles, Policy and Persistence

C.2 Extending No Persistence

D Stochastic Equilibrium and D.1 Non-Stochastic Equilibrium

D.2 Profits and Long-Run Growth

E Slopes and Eigenvalues and E.1 Slope Coefficients

E.2 Linearized DSGE Solution

E.3 Eigenvalue Conditions

E.4 Rouche’s Theorem Conditions

F Abstract Algebra and F.1 Homology Groups

F.2 Basic Categories

F.3 De Rham Cohomology

F.4 Marginal Costs and Inflation

G Further Keynesian Models and G.1 Taylor Pricing

G.2 Calvo Wage Phillips Curve

G.3 Unconventional Policy Settings

H Empirical Robustness and H.1 Parameter Selection

H.2 Phillips Curve

I Additional Evidence and I.1 Other Structural Parameters

I.2 Lucas Critique

I.3 Trend Inflation Volatility

9.1 Analytic Aspects

The first result is to establish, by analytic means, that the constraint induces irregularities in the derivative.



This proof only focuses on the wall of the crossing. It confirms the general idea that when a "rearrangement pattern" fails a function will not be differentiable.


Remark 20. This rules out the use of the standard non-stochastic Grobman-Hartman theorem, as described, in for example, Teschl [2012]. However, away from aπ = 1, the linearization can be viewed as an approximation to local dynamics about the singular measure, defined as where the appropriate generalization of (3)-(5) bind.



Proposition 19. The Calvo New Keynesian model, defined by the recursive equilibrium f µ a.e. in Proposition 4, is not continuously differentiable at ZINSS.



This paper is available on arxiv under CC 4.0 license.