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This study examines a wide variety of core indices of the consumer price index (CPI).
The quality of the indices is examined from the aspect of simplicity of calculation,
and their ability to describe and assess the current inflation environment and to predict
the future inflation environment. For the purpose of examining the appropriateness of
monetary policy ex post, and also to help determine policy for the future, it is
important to focus on core inflation, i.e., inflation excluding unexpected shocks that
are not affected by monetary policy.
The study reviews twenty-three indices, most of which are generally accepted in the
literature. In line with the findings in other countries, it was found that no single index
stands out as preferable to the others. The indices that give weight to the CPI's
components according to their variance and the index that trims twenty percent of the
upper and lower tails of the distribution contribute to the understanding of the current
inflation environment. The index that excludes energy and food prices, the index that
excludes also fruit and vegetable prices, and a more complex index based on an
estimate of a VAR system provide information that improves the ability to predict the
overall index.
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