On measuring the nonlinear effect of interest rates on inflation and output in Korea

While economists are interested in the reaction of the interest rate to changes in the inflation rate, central bankers are usually more interested in the reverse causal relationship, i.e., the response of inflation (and output) to a change in the official interest rate as administrated by the central bank. We investigate the reverse causal relationship in Korea by employing the LSTVAR model proposed by Weise (1999). We have found strong evidence in favor of nonlinearity. As a result, we discovered various types of asymmetric effects of the interest rate on inflation and output. An asymmetric effect of monetary shocks of different sizes was uncovered, which implies that when the unexpected change in the official rate is doubled (i.e. from 0.25%p to 0.5%p), its effect on inflation and output is likely to be more than doubled. However, this finding is upheld only when the economy is in recession. The opposite result, in which the effect is smaller, is supported when the economy is expanding. Regarding the other asymmetric effect of monetary shocks with different signs, we found that central banks can expect that increasing the official rate by some certain amount (e.g. 0.25%p) is likely to have much larger effect on inflation and output than decreasing the rate by the same amount (e.g. -0.25%p) regardless of the state of the economy.