Essays on Uncertainty, Asset Prices and Monetary Policy
: A Case of Korea

  • Paul Yi

Student thesis: Doctoral ThesisPhD


In Korea, an inflation targeting (IT) regime was adopted in the aftermath of the Korean currency crisis of 1997–1998. At that time, the Bank of Korea (BOK) shifted the instrument of monetary policy from monetary aggregates to interest rates. Recently, central bank policymakers have confronted more uncertainties than ever before when deciding their policy interest rates. In this monetary policy environment, it is worth exploring whether the BOK has kept a conservative posture in moving the Korean call rate target, the equivalent of the US Federal Funds rate target since the implementation of an interest rate-oriented monetary policy. Together with this, the global financial crisis (GFC) of 2007–2009 provoked by the US sub-prime mortgage market recalls the following question: should central banks pre-emptively react to a sharp increase in asset prices? Historical episodes indicate that boom-bust cycles in asset prices, in particular, house prices, can be damaging to the economy. In Korea, house prices have been evolving under uncertainties, and in the process house-price bubbles have been formed. Therefore, in recent years, central bankers and academia in Korea have paid great attention to fluctuations in asset prices. In this context, the aims of this thesis are: (i) to set up theoretical and empirical models of monetary policy under uncertainty; (ii) to examine the effect of uncertainty on the operation of monetary policy since the adoption of interest rate-oriented policy; and (iii) to investigate whether gradual adjustment in policy rates can be explained by uncertainty in Korea. Another important aim is (iv) to examine whether house-price fluctuations be taken into account in formulating monetary policy. The main findings of this thesis are summarised as follows. Firstly, as in advanced countries, the four stylised facts regarding the policy interest rate path are found in Korea: infrequent changes in policy rates; successive changes in the same direction; asymmetric adjustments in terms of the size of interest-rate changes for continuation and reversal periods; and a long pause before reversals in policy rates. These patterns of policy rates (i.e., interest-rate smoothing) characterised the central bank‘s reaction to inflation and the output gap as being less aggressive than the optimising central bank behavior would predict (Chapter 3). Secondly, uncertainty may provide a rationale for a smoother path of the policy interest rate in Korea. In particular, since the introduction of the interest rate-oriented monetary policy, the actual call money rates have shown to be similar to the optimal rate path under parameter uncertainty. Gradual movements in the policy rates do not necessarily indicate that the central bank has an interest-rate smoothing incentive. Uncertainty about the dynamic structure of the economy, which is dubbed ‗parameter uncertainty‘, could account for a considerable portion of the observed gradual movements in policy interest rates (Chapter 4). Thirdly, it is found that the greater the output-gap uncertainty, the smaller the output-gap response coefficients in the optimal policy rules, and in a similar vein, the greater inflation uncertainty, the smaller the inflation response coefficients. The optimal policy rules derived by using data without errors showed the large size of the output-gap and inflation response coefficients. This finding confirms that data uncertainty can be one of sources explaining the reasons why monetary policymakers react less aggressively in setting their interest rate instrument (Chapter 5). Finally, we found that house prices conveyed some useful information on conditions such as possible financial instability and future inflation in Korea, and the house-price shock differed from other shocks to the macroeconomy in that it had persistent impacts on the economy, consequently provoking much larger economic volatility. Empirical simulations showed that the central bank could reduce its loss values in terms of economic volatility, resulting in promoting overall economic stability when it responds more directly to fluctuations in house prices. This finding provides the reason why the central bank should give more attention to house-price fluctuations when conducting monetary policy (Chapter 6).
Date of Award15 May 2014
Original languageEnglish
Awarding Institution
  • University of Bath
SupervisorChristopher Martin (Supervisor) & Bruce Morley (Supervisor)


  • Uncertainty
  • Asset Prices
  • Monetary Policy
  • Inflation targeting
  • Interest-rate Smoothing
  • Monetary Policy Rules
  • New Keyensian Framework

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