Indice de precios al consumidor (Consumer Price Index).
The index is calculated monthly and covers urban households whose
head is a wage or salary earner with an average income.
Households with a high or very low per capita income are excluded, as
are one-person households.
1979 = 100.
Source of weights
Items were selected and weights determined on the basis of the results
of a household expenditure survey carried out during 12 months between
September 1977 and August 1978 and covering 1,985 households in the Lima
The items were selected using the following criteria: relative
importance within the sub-group, representative of price movements of
similar items and continuously available. The value of expenditure on
items not included in the basket was added to that of the selected items
either: (a) directly, by assigning it to another item with
similar characteristics, which was considered to be a substitute; or
(b) indirectly, by distributing the cost proportionately among the
other items in the sub-group.
Weights and composition
||Number of items
||Approximate number of price quotations
|Food and tobacco
|Clothing and footwear
|Rent, fuel, electricity
|Furniture, household equipment, cleaning materials
|Personal and medical care
|Transport and communication
|Education and recreation
|Other goods and services
Household consumption expenditure
Household consumption is defined as that part of expenditure on goods
and services which is designed to satisfy the needs of the family,
excluding the acquisition of housing and land, and all disbursements
which may generate income for households. Home-produced goods and
services consumed by the household are valued at market prices and
included in household consumption. Thus, for example, household
expenditure includes the imputed rent of owner-occupied housing.
Account is also taken of all payments that do not involve double
counting, for example the cost of car insurance provided the
repair costs of insured vehicles are not included.
Method of data collection
The results of a special National Institute for Statistics (INE) survey
were used to select the sample of outlets, on the basis of the number of
points of sale and the number of street vendors in the area. The sample
comprised 33 markets and four supermarkets. Commercial and service
establishments were selected from commercial streets or zones
in each district on the basis of their readiness to collaborate in the
survey and the range of products available. Account was also taken of
the large chains of supermarkets. The prices used to calculate the
index are those paid by housewives in markets or by most consumers in
establishments. The prices are recorded in supermarkets, retail outlets
and service establishments. Items with prices that vary considerably,
such as fresh produce (vegetables, tubers, fruits, fish, greens) and
those whose prices vary only very slightly but which are sold in large
public markets (rice, sugar, edible oils and fats, etc.) are priced each
week. Items with less varying prices, such as cereals, clothing,
furniture, etc, are priced each month. Rents, property prices and
municipal taxes are recorded twice a year. Public service charges are
recorded periodically. Some prices are obtained by direct purchase in
Data on house rents are obtained from a fixed sample of
households covered by the survey.
Specification of varieties
The selection of a given variety under a heading depends on its
importance within the category, the ease with which it can be
defined and priced and its continued availability over time.
The articles selected in the household survey do not always
have well defined characteristics, as regards trade marks, size,
etc. In order to compile initial samples for the purpose of
observation, the investigators visited the establishments in the sample,
and noted in detail the characteristics of the items selected: name,
trade mark, model, size or weight, etc. Where possible, the dealer was
asked which brand of the particular variety he sold most of. The sample
was then centrally controlled to ensure that the prices recorded
correspond exactly to those appearing in the sample.
Substitution, quality change, etc.
For various reasons, (e.g. the season, absence of traders,
discontinuity of items) it is not always possible to record prices for
all items. The National Institute for Statistics solves this problem as
follows: when a variety is homogeneous, an average price is used,
calculated on the basis of the prices collected for other similar items
during the period; when a variety is heterogeneous, the latest available
price is maintained if it is certain that the item will reappear in the
near future; if the item does not reappear after three months, it is
The index is computed according to the Laspeyres formula as a
weighted arithmetic average with fixed base, using weights
corresponding to September 1977-August 1978.
Price relatives of the current and previous periods are used to
compute item indices. Relatives of average prices are calculated for
homogeneous varieties, and averages of price relatives are used for
heterogeneous varieties. Simple arithmetic averages are calculated in
A new series is now computed (base 1990 = 100), but the relevant
methodological information was not available in the ILO at the time the
present volume was published.
Organisation and publication
Instituto Nacional de Estadística:
Indice de Precios al
Consumidor de Lima Metropolitana (Lima).
Indice de Precios al Consumidor de Lima
Metropolitana, Metodología, dic. 1980 (Lima).