Stochastic Equilibrium, the Phillips Curve and Keynesian Economics
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Cardiff University Doctoral Thesis Stochastic Equilibrium, the Phillips Curve and Keynesian Economics Author: Supervisor: David Staines Professor Huw Dixon A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Economics Section Cardiff Business School January 28, 2019 2 Abstract I uncover serious problems with the benchmark New Keynesian Phillips curve lin- earized around its non-stochastic zero inflation steady state when the underlying model features a subset of prices that stay rigid over multiple periods, as in the popular Calvo model. I am able to demonstrate that the dynamics of approxima- tions taken at the non-stochastic steady state are non-hyperbolic. This means that approximations taken at this point do not represent a valid description of the dy- namics of the underlying model at any other point in the state space. This allows me to overturn results such as the ’Divine Coincidence’ that equates welfare under price rigidity with the level prevailing under price dispersion. I introduce a dynamic stochastic concept of equilibrium that can be applied to New Keynesian models and offers a natural point to take approximations to analyze business cycle dynamics. It is methodologically interesting as it is a notion of general equilibrium that does not correspond to partial equilibrium. Keywords: Macroeconomics, Mathematical Economics, Random Dynamical Sys- tems, General Equilibrium, Monetary Policy JEL Classification: C6, D5, E1, E3, E5 2010 Mathematics Subject Classification: 37Axx, 37Bxx, 37Cxx, 37Dxx, 37Gxx, 37Hxx. 3 Declaration of Authorship DECLARATION This work has not been submitted in substance for any other degree or award at this or any other university or place of learning, nor is being submitted concurrently in candidature for any degree or other award. Signed . (candidate) Date . STATEMENT 1 This thesis is being submitted in partial fulfillment of the requirements for the degree of PhD Signed . (candidate) Date . STATEMENT 2 This thesis is the result of my own independent work/investigation, except where otherwise stated. Other sources are acknowledged by explicit references. The views expressed are my own. Signed . (candidate) Date . STATEMENT 3 I hereby give consent for my thesis, if accepted, to be available for photocopying and for inter-library loan, and for the title and summary to be made available to outside organisations. 4 Signed . (candidate) Date . STATEMENT 4 I hereby give consent for my thesis, if accepted, to be available for photocopying and for inter-library loan, and for the title and summary to be made available to outside organisations. Signed . (candidate) Date . 5 Acknowledgements I would like to thank the Economic and Social Research for offering me a scholarship that was essential to fund my research. Support staff, such as, Elsie Phillips and Lainey Clayton who have borne some of my foibles for the last five years and helped me through the PhD scheme. I would like to thank Professor Huw Dixon for his en- couragement and insightfulness. Patrick Minford for helpful comments and imparting some of his passion both for DSGE modeling and macroeconomic debate. All of the staff in the Economics Section at Cardiff have given me excellent support and advice. That has helped me grow as an economist. Furthermore, I have benefited a great deal from discussion and debate with other economists Michael Hatcher, Ceri Davis, Lorant Kaszab, Tom Wilkinson, Ashley Nanton, Antony Savagar, Tamas Csabafi, Craig Thamotheram, Tim Jackson, Tian Maoshan, George Melios, Nikos Tzivanakis and Dandan Wang come first to mind. I would also like to thank my friends in other sections of the business school and across the university who have enriched my life greatly during my time in Cardiff. Finally, I would like to thank my examiners for comments and corrections that greatly improved and extended the analysis. Any remaining errors are my own. 7 Dedicated to my parents, my grandmother and my closest friends 9 Contents Declaration of Authorship2 1 Introduction 13 2 New Keynesian Framework 19 2.1 Household’s Problem............................ 19 2.1.1 Aggregate Allocation........................ 19 2.1.2 Individual Product Demand.................... 23 2.2 Firms’ Problem............................... 24 2.2.1 Cost Minimization......................... 25 2.2.2 Optimal Price Setting....................... 26 2.2.3 Flexible Price Equilibrium and Zero Inflation Non-Stochastic Steady State............................ 27 2.2.4 Future Marginal Costs and Nominal Rigidity.......... 28 2.3 Price Dispersion and Aggregation..................... 30 2.4 Policy Rule................................. 31 2.5 Formalization Calvo Model........................ 35 2.6 Forward-Solution Phillips Curve ZINSS................. 39 2.6.1 Persistence Problem........................ 42 2.7 Alternative Models and Equivalences................... 48 2.7.1 Lucas Model............................ 48 2.7.2 Rotemberg Pricing......................... 54 2.7.3 Equivalence Conditions and Policy Implications......... 55 3 The Role of Price Dispersion 59 3.1 Lower Bound on Price Dispersion..................... 59 3.1.1 Different Pricing Models...................... 61 10 Contents 3.1.2 Stochastic Extension........................ 66 3.2 Persistence Properties........................... 67 3.2.1 Price Dispersion with Calvo Pricing............... 67 3.2.2 Price Dispersion with Taylor Contracting............ 71 3.2.3 Applications............................ 73 3.3 Non-Negativity and Poles......................... 75 3.4 Market Failure New Keynesian Model.................. 77 4 Stochastic Equilibrium 83 4.1 Ergodic Theory............................... 84 4.2 Existence of Stochastic Equilibrium.................... 98 4.3 Characterizing the Steady State...................... 99 4.3.1 Comparative Statics........................ 103 4.3.2 Non-Stochastic Steady State with Trend Inflation........ 103 4.4 Theoretical Significance and Extensions................. 115 5 Valid and Invalid Approximation 121 5.1 Bifurcation, Valid Approximation and Non-negativity......... 121 5.2 Hyperbolicity................................ 125 5.2.1 Valid Approximation: Stochastic Grobman Hartman...... 128 5.3 Log-Linearization and NKPC....................... 130 5.3.1 Basic Phillips Curve Solution................... 131 6 Thesis Conclusion 143 7 Appendices 145 7.1 Results from Chapter 2.......................... 145 7.1.1 Mathematics of GSM....................... 145 7.1.2 Proof Lemma 1........................... 146 7.1.3 Taylor (1979)............................ 149 7.1.4 Eigenvalues and Convergence................... 151 7.1.5 Full Solution for Benchmark Model................ 152 7.2 Proofs from Chapter 3........................... 153 7.2.1 Proof of Proposition 5....................... 153 Contents 11 7.2.2 Definition 1 and Lemma 3 Material................ 157 7.2.3 Taylor Pricing Example...................... 157 - 13 Chapter 1 Introduction The macroeconomic profession has broadly settled on a New Neo-Classical Synthesis, Goodfriend and King[1997]. This approach adds imperfect competition and staggered price adjustment to the skeleton of the Real Business Cycle model to generate micro- founded compliments to the aggregate demand and aggregate supply equations of Old Keynesian economics. The Euler equation specifying optimal consumption and the optimal price-setting relation - the New Keynesian Phillips curve (NKPC) - simplify to their Old Keynesian counterparts when non-contemporaneous exogenous variables are held fixed. When this constraint is relaxed, it is necessary to specify an interest rate rule consistent with the "Taylor Principle" to generate stable solution paths.1 Thus a three equation set up emerges. The combination of rational expectations with monetary non-neutrality allows one to analyze systematic monetary policy seemingly unhindered by the Lucas Critique, Lucas Jr[1976]. For this reason, the three equation New Keynesian framework un- derpins the field of Dynamic Stochastic Equilibrium (DSGE) modeling , now popular in academia and widely used by Central Banks. Nevertheless, New Keynesianism has had problems distinguishing itself from the Neo-Classical tradition in terms of policy prescriptions and model predictions. Macroe- conomics as a separate intellectual discipline came into existence following The Gen- eral Theory of Employment, Interest and Money (Keynes[1936]), in order to learn how best to mitigate inefficient business cycle fluctuations. The lack of inefficient 1The "Taylor Principle" states that the real interest rate should be expected to increase in response to higher inflation in order to drive it back to target following a shock to expectations to prevent indeterminacy in the linear system associated with sunspot equilibria, see Woodford[2001]. The term was coined in respect of the seminal work on monetary policy rules Taylor[1993a]. Simultaneously, Henderson and McKibbin[1993] proposed a similar rule, which I will discuss later. 14 Chapter 1. Introduction fluctuations in benchmark Real Business Cycle models, such as Long Jr and Plosser [1983] and Barro and King[1984], is the most unappealing aspect of Neo-Classical modeling and the reason why it has never enjoyed favor in policy circles. Unfortunately, comparable New Keynesian models also suffer from this problem. Correia et al.[2008] show that the Central Bank can implement the social optimum when the government is using a standard set of distortionary tax instruments to correct