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MAIN CONCEPTUAL DIFFERENCES FROM THE CPI
4 A living cost index reflects changes over time in the purchasing power of the after-tax incomes of households. It measures the impact of changes in prices on the out-of-pocket expenses incurred by households to gain access to a fixed basket of consumer goods and services. The Australian Consumer Price Index (CPI), on the other hand, is designed to measure price inflation for the household sector as a whole and is not the conceptually ideal measure for assessing the changes in the purchasing power of the disposable incomes of households.
5 There are a number of ways to construct a price index for households with at least three widely accepted approaches used by national statistical agencies:
6 From the September quarter 1998, the CPI has been constructed using the acquisitions method. The ALCIs have been constructed using the outlays approach.
7 The item coverage of a living cost index is determined by reference to the actual money outlays of households on all but investment items.
8 In practice, for most goods and services purchased by the reference population, outlays and acquisition occur within a relatively short space of time. There are three areas of expenditure in which these conceptual approaches provide significantly different results:
9 Under the acquisitions approach used in the CPI, the net purchase of housing and the increase in volume of housing due to renovations and extensions and other costs (e.g. maintenance costs and council rates) are included for owner-occupied housing. Changes in rental are measured for that part of the reference population that resides in rented dwellings. The CPI does not include interest paid on mortgages.
10 Under the outlays approach used in the ALCIs, the changes in the amount of interest paid on mortgages (measured as part of financial and insurance services) and other costs (e.g. maintenance costs and council rates) are included for owner-occupied housing. In addition, changes in rental are measured for that part of the reference population that resides in rented dwellings. The ALCIs do not include the net purchase of housing and the increase in volume of housing due to renovations or extensions.
11 Insurance (other than health insurance) is treated differently in the ALCIs. Under the acquisitions approach, the weight for insurance in the CPI relates to the value of the service provided by the insurance company. In simple terms, this represents the amount of premiums paid by households less the amounts reimbursed by way of claims. Under the outlays approach used in the ALCIs, the weight relates to the gross value of insurance premiums paid by households.
12 Financial services are treated differently in the ALCIs. Mortgage interest and consumer credit charges are included in the ALCIs. However other financial services (i.e. deposit and loan facilities and other financial services) are not included.
13 Regional weights for the CPI are based on the HES distributions in the capital cities, however the weights in the analytical living cost indexes are based on the HES distributions for the State or Territory. This produces more reliable weights for some of the smaller expenditure categories in these living cost indexes.
14 Construction of the ALCIs was undertaken in three stages. Stage one was concerned with calculating weights representative of the expenditure patterns of the defined household types. Stage two involved identifying appropriate measures of price change for each of the expenditure weights. The third and final stage was to use the weights to aggregate or average the price change measures.
15 Item weights for the population subgroups were derived mainly from the 2003-04 HES. However, unlike the CPI where estimates are calculated separately for each of the eight capital cities, population subgroup estimates were calculated at the national level only. This was necessary because the subgroup sample sizes at the capital city level were simply too small, for at least some groups, to produce reliable estimates at the capital city level. For this reason it is not possible to produce living cost indexes at the individual city level.
16 The measures of price change, with the exception of those for interest charges, were sourced from the CPI. Most item price indexes were constructed by direct reference to the equivalent CPI expenditure class indexes. Expenditure classes are the lowest level at which the expenditure weights are fixed for the duration of an index series.
17 Some item price indexes were constructed by reference to lower level CPI price data. Such exceptions relate to those items where it is known that different household types face different prices, such as subsidised public transport fares and pharmaceuticals for senior citizens.
18 Price measures for interest charges have been maintained separately by the ABS on a basis comparable with those employed in the CPI prior to the September quarter 1998.
19 For ease of comparison, the index reference period for the CPI data used throughout this publication has been re-referenced to June quarter 1998 = 100.0. Index numbers and percentage changes are always rounded to one decimal place. The percentage changes are calculated from the one decimal place index numbers. Index numbers for periods longer than a single quarter (e.g. for financial years) are calculated as the simple arithmetic average of the rounded quarterly index numbers. All index numbers and percentage changes shown are calculated on this basis. This may lead to some minor differences (due to rounding) from the figures published in Consumer Price Index, Australia (cat. no. 6401.0).
20 The ALCIs were constructed using three sets of weights. The first set of weights, based on the 1993-94 HES, was used to construct the indexes from the June quarter 1998 to the June quarter 2000. The second set of weights, based on the 1998-99 HES, was used to construct the indexes from the June quarter 2000 to the June quarter 2005. The third set of weights, based on the 2003-04 HES, was used to construct the indexes from the September quarter 2005 onwards.
EXPENDITURE PATTERNS OF THE SELECTED HOUSEHOLD TYPES
21 Calculation of the aggregate impact of price changes on each of the household types involves weighting together the price movements recorded for individual goods and services. For each household type, the weight assigned to any particular good or service reflects the proportion of total household expenditure accounted for by expenditure on the item.
22 Table 1 shows average weekly expenditure per household during 2003-04 for each of the four household types, at June quarter 2005 prices. The commodity groups used correspond to the commodity groups used for the current (15th series) CPI.
23 Table 1 illustrates significant differences in expenditures, both in total and at the individual commodity group level across the household types. Although differences in incomes are likely to be a major reason for this, other factors such as the demographic make-up of the households and dwelling tenure would also play a part. For example, age pensioner households have on average the lowest number of persons per household and self-funded retiree households have a higher than average rate of outright home ownership.
24 Table 2 presents the same data in percentage terms, along with the CPI for comparison purposes. It is this expenditure data that produces the expenditure shares or weights that are given to each household type, and to which the price movements are applied.
25 There are some notable differences in the expenditure weights across the household types. For example, the proportion of expenditure allocated to Food is highest for age pensioner households. It is also relatively high for other government transfer recipient households. Employee households allocate a higher proportion of their expenditure to Transportation, Education and Financial and insurance services (which includes interest charges) than the other household types. Other government transfer recipients allocate higher proportions of their expenditure to Housing, Alcohol and tobacco and Communication. Self-funded retiree households have higher relative expenditure on Household contents and services and Recreation than the other household types. Health costs account for a significantly higher proportion of expenditure of age pensioner and self-funded retiree households.
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