The reference population was defined as the total number of private households situated in the urban areas of 13 cities; single-person households and collective households were excluded because of their special consumption patterns, as well as very high-income households with widely varying consumption patterns (such exclusions account for 5 per cent of all households surveyed in each city).
Items were selected on the basis of the following criteria: the relative weight of the expenditure: at least 5 per cent within the group; frequency of acquisition observed: the item must be purchased by more than 30 per cent of households; the feasibility of identification, &ie of observing prices and quantities purchased.
The weights were not adjusted to take account of price changes between 1984-1985 and 1988.
Major groups | Number of items | Weights | Approximate number of price quotations |
---|---|---|---|
Food | 77 | 42.58 | 2540 |
Housing: | @ | @ | 7341 |
Rent | 1 | 19.35 | ... |
Fuel, light and water | 5 | 4.82 | ... |
Furniture, furnishings, cleaning products, household linen | 28 | 7.14 | ... |
Clothing | 24 | 8.16 | 1715 |
Medical care | 13 | 3.30 | 1037 |
Education and recreation | 18 | 4.79 | 990 |
Transport and communication | 12 | 4.03 | 420 |
Miscellaneous | 16 | 5.84 | 1039 |
Total | 194 | 100.00 | 15082 |
Following the exclusion of this expenditure, which is taken into account in the survey on incomes and expenditure but which does not correspond to the concept of consumption expenditure, the remaining expenditures were grouped together into categories according to production function and in line with the structure of the price index.
Income in kind consumed by the households is imputed to the expenditure on the relevant goods and services; owner-occupied housing is imputed to the weights of rent, but only rent data are collected. The purchase of used goods is treated as any other acquisition; social security contributions are considered as a deduction from income.
Rentsub-group under the
Housingmajor group: tenants are asked directly how much they pay for the rent of their housing.
Other sources include the municipal public undertakings which provide information on the rates applied for water, sewage, electricity and telephone services, and town halls which provide the decrees establishing the rates applicable on the urban transport system.
For food prices, the month is divided into three equal periods in which data are obtained from one-third of each group. Thus, although the sources are surveyed each month, prices are obtained in three periods throughout the month. Data are collected each month for items such as public services (water and sewage services, electricity and telephone) and airline tickets, the cost of which varies from month to month.
Where establishments provide data during visits by agents, prices are collected every month except for the following items:
These periodicities were established because of the relative variability of prices of goods and services over time.
For some items (gas, cooking paraffin, petrol for automobiles, lotteries and cinema admission in particular) prices are collected in the period in which the variation occurs.
The prices observed or collected are those paid by the consumer for goods or services on sale for cash in retail outlets at the time when the data are collected at the source establishment.
House rent includes only the cost of the actual rent of private households. Data are collected by means of direct interview. Owner-occupied dwellings are not surveyed.
change of referenceprocedure is used; this method enables variations in prices due to a change in the specification of the item or the source of information to be cancelled out. However, for the
clothingsub-groups, in which the references and specifications are subject to many changes, each new element appearing in the collection of data is analysed to enable a decision to be taken regarding the validity of the price variation recorded.
The index for an aggregate (sub-group, group, city, the whole country) is the weighted average of the elementary indices, with the weights used in the computation of the index corresponding to the structure of expenditure by low-income families in the various spatial units (13 cities) covered.
Detailed sub-groups are published.
Boletín Mensual de Estadística(Bogotá).
Idem:
Boletín Mensual de Estadística
(Bogotá) No. 433, April
1989 (for more detailed methodological information).