Interest rate control in a model of monetary policy

A monetary economy comprises a vast array of market-clearing interest rates. Central banks exert a direct influence over only a narrow subset of these rates: the rate at which they supply marginal funds to the commercial banking system. Accordingly, the market interest rates which impinge upon real activity are typically distinct form - though not independent of - the official interest rate. This paper develops a formal model of the interactions between the central bank, commercial banks and the non-bank private sector. This model is then used to analyse the relationship between the official interest rate and 'other' market rates. Some illustrative evidence on the extent of the imperfection in the UK authorities' interest rate control is also considered. Two policy conclusions emerge. First the authorities must understand the nature of the feed-through of official interest rates into market rates when deciding on the appropriate level of the monetary instrument. Second, the possibility that interest rates may not all move perfectly in line, implies that policy-makers and commentators alike need to be conscious of this plurality of interest rates when assessing the overall tightness or looseness of monetary conditions.