Up until October 1998, the RBA's inflation target was defined in underlying terms. That is, the RBA's goal was to keep "underlying inflation" between 2 and 3% in the medium term - generally taken to mean over the course of an economic cycle. In the past, the headline rate of inflation was affected by a number of factors, not all of them related to inflationary effects in the economy. Reflecting such concerns, the Treasury some years ago developed an underlying CPI measure. This measure excluded from the headline measure prices of items that were affected by interest rates, of goods such as fruit and vegetables, and imported oil, whose price fluctuations have little to do with the state of the Australian economy, of publicly-owned items (such as public rents), and of tobacco and alcohol.
In September 1998, however, the RBA redefined the target in terms of simply maintaining an "average rate of inflation, as measured by the CPI (headline rate of inflation), of 2-3 per cent over the medium term." As part of its periodic review of the CPI, the Australian Bureau of Statistics had made a number of changes to the CPI, the major one of which was taking out mortgage interest charges. These changes reduced the problems in using the headline CPI to evaluate monetary policy. As such, the RBA's target is now considered in terms of the headline rate of inflation. This is not to say that the RBA will discontinue analysing underlying inflation. Rather, the RBA will still make an assessment of whether the CPI has been affected by temporary fluctuations in prices, or changes in taxes and administrative charges, and consider the way monetary should, or shouldn't react to such changes