The Bank of Canada uses core CPI inflation, the year-over-year rate of change of the consumer price index excluding food, energy, and the effects of changes in indirect taxes, as the operational guide for monetary policy. In this report we study the concept and measurement of core or underlying inflation more generally by examining several alternative measures of core inflation, from the viewpoint that core inflation is a tool for policy purposes, either as an indicator of current and future trends in inflation, or as a viable target for monetary policy. A simple model of price determination is proposed that defines the core conceptually, and illustrates the process by which aggregate inflation rates may differ from the core.

As a measure of inflation for policy purposes, core inflation is useful to the extent that it can be measured accurately. Therefore, following a discussion of conceptual issues, the report's focus narrows and we introduce the various measures of core inflation, concluding with a comparative evaluation of those measures. We find the alternatives quite similar in many respects. However, a closer assessment based on their suitability to various policy purposes suggests that different measures do well along different dimensions.