第八铨
Core inflation came to be defined as the 12-month rate of increase in the CPI excluding food, energy, and the effects of changes in indirect taxes (CPIXFET). While the objective of monetary policy is to control the rate of total CPI inflation, there are good theoretical reasons to use a concept of core inflation as an operational guide for monetary policy. Some of the goods and services included in the total CPI have very volatile prices. The measure of core inflation eliminates these negative effects. Another reason for the focus on core inflation is to see through the effects of changes in indirect taxes, such as sales and excise taxes, while total CPI inflation take it into account. These effects of indirect taxes are increase in the price level that is proportional to the tax increase, which raises inflation temporarily. Core inflation also tends to be a better indicator of future inflation developments than total CPI inflation because it takes about a year before monetary actions have any significant effect on inflation.
The core inflation excludes the 8 most volatile of the 54 components from the total CPI and then adjusts the remaining components to remove the effect of changes in indirect taxes. The 8 components excluded are fruit, vegetables, gasoline, fuel oil, natural gas, intercity transportation, tobacco, and mortgage-interest costs.
In practice, there are various ways to measure the underlying trend in inflation. The focus on core inflation as an operational guide is consistent with targeting the total CPI because, over longer periods of time, the rates of increase in the total CPI and the core inflation have tended to move in a very similar fashion and is likely to continue to do so in the future. So achieving the target rate of increase for the core CPI will tend to bring about a similar rate of increase in the total CPI over time.