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BRIEF DESCRIPTION OF THE CPI
2 The capital city indexes measure price movements over time in each city individually. They do not measure differences in retail price levels between cities.
3 Further information about the CPI is contained in the booklet A Guide to the Consumer Price Index, 14th Series (Cat. no. 6440.0) which is available on the ABS Website, or from the ABS on request.
4 The frequency of price collection by item varies as necessary to obtain reliable price measures. Prices of some items are volatile (i.e. their prices may vary many times each quarter) and for these items frequent price observations are necessary to obtain a reliable measure of the average price for the quarter. Each month prices are collected at regular intervals for goods such as milk, bread, fresh meat and seafood, fresh fruit and vegetables, petrol, alcohol, tobacco and holiday travel and accommodation. For most other items, price volatility is not a problem and prices are collected once a quarter. There are a few items where prices are changed at infrequent intervals, for example education fees where prices are set once a year. In these cases, the frequency of price collection is modified accordingly.
5 In order to facilitate a more even spread of field collection workload the bulk of the items for which prices are collected quarterly are priced in the first two months of each quarter (i.e. July/August, October/November, January/February, April/May). With a few exceptions items priced in the third month are those subject to price changes at discrete points of time (e.g. electricity and postal charges); in these cases information about any changes in price during the quarter is obtained so that an average price for the whole quarter can be calculated.
6 There are 89 expenditure classes (that is, groupings of like items) in the fourteenth series CPI and each expenditure class has its own weight, or measure of relative importance. In calculating the index, price changes for the various expenditure classes are combined using these weights.
7 Changes in the weighting pattern have been made at approximately five-yearly intervals to take account of changes in household spending patterns. The CPI now comprises fourteen series of price indexes which have been linked to form a continuous series. The current weighting pattern for the CPI is given in A Guide to the Consumer Price Index, 14th Series (Cat. no. 6440.0).
ANALYSIS OF CPI CHANGES
8 Movements in indexes from one period to another can be expressed either as changes in index points or as percentage changes. The following example illustrates the method of calculating changes in index points and percentage changes between any two periods:
All groups CPI: Weighted average of eight capital cities.
9 Percentage changes are calculated to illustrate three different kinds of movements in index numbers:
10 Table 7 provides a detailed analysis, for the weighted average of eight capital cities, of movements in the CPI since the previous quarter, including information on movements for groups, sub-groups and expenditure classes. It also shows the contribution which each makes to the total CPI. For instance, the dairy and related products sub-group contributed 2.00 index points to the total All groups index number of 136.6 for March Quarter 2002. The final column shows contributions to the change in All Groups index points by each group, sub-group and expenditure class.
11 Various series are presented in Tables 8, 9 and 10 in this publication which are helpful for analytical purposes. These series are compiled by taking subsets of the CPI basket. (A complete list of CPI groups, subgroups and expenditure classes is contained in Tables 6 and 7.)
12 Some of the compiled series are self explanatory, such as ‘All groups excluding Food’. Other series and their composition are described below:
All groups, goods component: comprises the Food group (except Restaurant meals), Alcohol and tobacco group, Clothing and footwear group (except Clothing services and shoe repair) and Household furnishings, supplies and services group (except Household services); the Utilities, Audio, visual and computing and Books, newspapers and magazines sub-groups; and the House purchase, Pharmaceuticals, Motor vehicles, Automotive fuel, Motor vehicle parts and accessories, Sports and recreational equipment, Toys, games and hobbies, Pets, pet foods and supplies and Toiletries and personal care products expenditure classes.
All groups, services component: comprises all items not included in the ‘All groups, goods component’.
All groups, tradables component: comprises all items whose prices are largely determined on the world market.
All groups, non-tradables component: comprises all items not included in the 'All groups, tradables component'.
All groups excluding ‘volatile items’: comprises the All groups CPI excluding Fruit and vegetables and Automotive fuel.
Market goods and services excluding ‘volatile items’: in addition to the items excluded from the series "All groups excluding ‘volatile items’", also excludes: Utilities, Property rates and charges, Health, Other motoring charges, Urban transport fares, Postal, Education and Child care.
13 A detailed description of the special and analytical series was published in Appendix 1 to the September quarter 2000 issue of Consumer Price Index, Australia (Cat. no. 6401.0). The ABS is grateful for the assistance of the Reserve Bank of Australia for specifying the items included in the "All groups excluding ‘volatile items’" and "Market goods and services excluding ‘volatile items’". The Reserve Bank of Australia does not accord any special policy status to these series.
14 In analysing price movements in Australia, an important consideration is Australia's performance relative to other countries. However, due to the many differences in the structure of the housing sector in different countries and in the way that housing is treated in their CPIs, a simple comparison of All groups (or headline) CPIs is often inappropriate. To provide a better basis for international comparisons, the Fourteenth International Conference of Labour Statisticians adopted a resolution which called for countries to ‘provide for dissemination at the international level of an index which excludes shelter, in addition to the all-items index’.
15 Table 11 presents indexes for selected countries on a basis consistent with the above resolution and broadly comparable to the Australian series ‘All groups excluding Housing’. To facilitate comparisons all indexes in this table have been converted, where necessary, to a quarterly basis and re-referenced to a base of 1989-90 = 100.0.
16 In producing Table 11, the ABS is grateful for the assistance of the relevant national statistical agencies which have either directly supplied indexes for all items excluding shelter or data to enable their derivation.
17 Current publications produced by the ABS are listed in the Catalogue of Publications and Products, Australia (Cat. no. 1101.0). The ABS also issues, on Tuesdays and Fridays, a Release Advice (Cat. no. 1105.0) which lists publications to be released in the next few days. The Catalogue and Release Advice are available from any ABS office.
18 Users may also wish to refer to the following publications:
19 As well as the statistics included in this and related publications, the ABS may have other relevant unpublished data available. Inquiries should be made to Steve Whennan on 02 6252 6251 or to the National Information and Referral Service on 1300 135 070.
SYMBOLS AND OTHER USAGES
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