[G1] Consumer price inflation

G1 CONSUMER PRICE INFLATION

The data are from ABS Cat No 6401.0. Percentage changes are calculated from the indices published in ABS Cat No 6401.0.

The ‘All groups’ measure is the total or ‘headline’ consumer price index. Prior to the September quarter 1948, the series is compiled using the Australian Statistician's 'C Series' Retail Price Index (RPI). This series is equivalent in coverage to the 'A Series' RPI but broader in scope insofar as it records the prices of a wider range of goods. Consumption weights for this series were not updated after 1936. Also, for annual data from the September quarter 1946 to the June quarter 1948, the 'C Series' RPI is used but with its rents component replaced by the housing group of the CPI. From the September quarter 1948 onwards, the series used is the CPI published by the ABS. This was introduced in 1960 and compiled retrospectively. For further information see http://www.rba.gov.au/calculator/calc_dataSource.jsp.

The seasonally adjusted quarterly percentage change of the ‘All groups’ measure is calculated by the RBA prior to 1987 using seasonal factors published by the ABS.

The 'All groups excluding interest and tax changes of 1999–2000' measure is calculated by the RBA. The adjustments made are the same as those made in Heath, Roberts and Bulman (2004), 'Inflation in Australia: Measurement and Modelling', The Future of Inflation Targeting, Proceedings of a Conference, Reserve Bank of Australia, Sydney, pp 167-207.

The ‘All groups excluding volatile items’ measure is the CPI (all groups) less fruit, vegetables, automotive fuel (and deposit & loan facilities to June 2011) adjusted by the RBA for the tax changes of 1999–2000. This measure is calculated by the RBA prior to 1987. The seasonally adjusted percentage change is calculated by the RBA using seasonal factors published by the ABS.

The ‘Tradables’ measure comprises all items in the CPI (all groups) whose prices are largely determined on the world market. Data for the period prior to 1998/99 are calculated by the RBA. The ‘Tradables excluding volatile items and tobacco' measure, which is calculated by the RBA, is equal to the ‘Tradables’ measure after fruit, vegetables, automotive fuel and tobacco are excluded. The ‘Non-tradables’ measure is all items in the CPI (all groups) excluding interest charges prior to the September quarter 1998 and excluding items in the ‘Tradables’ measure. Data for the period prior to 1998/99 are calculated by the RBA. The 'Non-tradables excluding deposit & loan facilities' measure, which is calculated by the RBA, is equal to the 'Non-tradables' measure after deposit & loan facilities are excluded to the June quarter 2011. All four measures are adjusted by the RBA for the tax changes of 1999–2000. There are breaks at September 2011 and December 2016 when the classification of tradable and non-tradable was updated. The seasonally adjusted quarterly percentage changes for ‘Tradables excluding volatile items and tobacco' and 'Non-tradables excluding deposit & loan facilities' are calculated by the RBA using seasonal factors published by the ABS.

The ‘Weighted median’ and ‘Trimmed mean’ are calculated by the ABS using the component level data of the consumer price index, which has been seasonally adjusted where appropriate. Both measures exclude interest charges prior to the September quarter 1998 and are adjusted for the tax changes of 1999–2000. The ‘Trimmed mean’ is calculated by ordering all the CPI components by their price change in the quarter and taking the expenditure-weighted average of the middle 70 per cent of these price changes. The ‘Weighted median’ is the price change in the middle of this ordered distribution, also taking expenditure weights into account. Further detail on the methodology can be found in Appendix 3 of the ABS Information Paper 'Seasonal Adjustment of Consumer Price Indexes, 2011'.

For further information on the various measures of underlying consumer price inflation, refer to ‘Box D: Underlying Inflation’, Statement on Monetary Policy, May 2002; ‘Box D: Measures of Underlying Inflation’, Statement on Monetary Policy, August 2005; and Roberts (2005), ‘Underlying Inflation: Concepts, Measurement and Performance’, Reserve Bank of Australia Research Discussion Paper No 2005-05.