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CPI reviewed at five-yearly intervals

Like any other long-standing and important statistical series, the CPI is reviewed from time to time to ensure that it continues to meet community needs. The ABS undertakes these reviews at approximately five-yearly intervals with timing generally linked to the availability of results from the HES.

While an important objective of these reviews is to update item weights to reflect changes in the range of available goods and services and changes in household spending patterns, these formal reviews also provide an opportunity to reassess the scope and coverage of the index and other methodological issues.

Following these reviews, the new CPI series is linked to the old to form a continuous series. This linking is carried out in such a way that the resulting continuous series reflects only pure price change and not differences in the cost of the old and new baskets.

The reference base period for the CPI is also updated, but at less frequent intervals. Changes in reference base periods have no effect on percentage changes, which are calculated from the index numbers.

Latest review of CPI in 1998

The latest review of the CPI concluded in the September quarter 1998. A major outcome of the review was the decision that the CPI would change from a measure of the change in living costs of employee households to a general measure of price inflation for the household sector. Consequently the population coverage was expanded from wage and salary earner households to include all metropolitan households. Weights were revised to reflect new expenditure patterns (based on the 1993–94 HES) and the expanded population coverage.