In this paper, the author calculates new measures of the trend inflation rate using changes in the components of total CPI; the hypothesis is that extreme fluctuations in certain prices reflect temporary supply shocks rather than any basic price trend. The trend inflation rate is measured by the weighted median of changes in the components of total CPI, or by the weighted average of their distribution, truncated by a certain percentage on each side, so that extreme variations are eliminated from the inflation rate as measured by total CPI (or their effect is attenuated, in the case of the weighted median).

The pattern of changes in these new measures over the period under study is similar to that for changes in CPI excluding food, energy and the effect of indirect taxes. This result is reassuring, because it suggests that if one of these new measures represents the actual trend inflation rate, then the Bank of Canada's reference index has been a good indicator for the conduct of monetary policy. This analysis also suggests that calculations of the trend inflation rate do not need to exclude all food prices from the overall index, since nearly half of those prices show little fluctuation. On the other hand, the exclusion of energy prices from total CPI is motivated by the fact that more than 70 per cent of energy products show strong price fluctuations. Finally, inter-city transportation costs, mortgage interest costs and tobacco product prices are among the components most often eliminated from measures of trend inflation.