Learning Dynamics and the Stabilization Policy in an Overlapping Generations Model

Taisei Kaizoji
Division of Social Science, International Christian University, Tokyo
Kaizoji@icu.ac.jp

Abstract

The purpose of this paper are (i) to analyze the dynamics in a simple OLG model characterized by a temporary equilibrium relation described by tex2html_wrap_inline28 , where tex2html_wrap_inline30 is real balance, tex2html_wrap_inline32 is expected value of tex2html_wrap_inline34 and tex2html_wrap_inline36 is the offer curve as in Grandmont (1985) in which agents use a simple adaptive learning rule of the form tex2html_wrap_inline38 . These two relations yield a one-dimensional adaptive learning dynamics

equation16

and (ii) to compare the adaptive learning dynamics generated by the equation (1) to a simple least squares learning scheme where agents would know the law of the dynamics tex2html_wrap_inline40 , and choose tex2html_wrap_inline42 so as to minimize the sum of the squares of past forecasting errors, that is,

equation22

First, we analyze bifurcations and chaos of the learning dynamics (1), which would clearly distinguish between the influence of the income effect and that of the error correction parameter tex2html_wrap_inline42 . We demonstrate that (i) if the income effect is weak, then the stationary monetary equlibria are globally stable when tex2html_wrap_inline42 is less that 2, and (ii) if the income effect is strong, then cyclic and chaotic learning dynamics occur under tex2html_wrap_inline48 . In other word, we demonstrate that the income effect and the error correction parameter offers the key to an understanding of the learning dynamics.

Then we illustrate that (iii) a least squares learning (2) for the error correction parameter tex2html_wrap_inline42 , is able to lead to the stationary moneraty equilibrium, provided that the endogenous fluctuations are caused by the strong overractionary expectations, that is, tex2html_wrap_inline52 , and on the contrary (iv) the least squares learning cannot lead to the stationary monetary equilibrium, provided that the endougenous fluctuations are caused by the strong income effect.

Finally we show that (v) a stabilization policy can stabilize an unstable learning dynamics when the least squares learning cannot lead the economic system to the stationary monetary equilibrium.


Society of Computational Economics
Second International Conference on Computing in Economics and Finance
Geneva, Switzerland, 26-28 June 1996