Japan
Official title
Consumer Price Index.
Scope
The index is compiled monthly and covers households in the entire
country, excluding one-person households and households mainly
engaged in agriculture, forestry and fishing.
Official base
1990 = 100.
Source of weights
The weights were derived from a household expenditure survey
conducted in 1990, covering approximately 8,000
households. The monthly weights of fresh food items (i.e. fresh fish,
fresh vegetables and fresh fruit) were obtained from
average expenditure data for 1989 and 1990. Index items were
selected according to the relative importance of each item to the
total consumption expenditure (0.01 per cent or more, in
principle), representativeness of price movements and continuity
of price data collection. The weights of items not priced were
allocated to the priced items representing them.
Weights and composition
| Major groups
| Number of items
| Weights
| Approximate number of price quotations
|
| Food
| 215 | 3140 | ...
|
| Housing
| 23 | 1478 | ...
|
| Fuel, light and water
| 6 | 553 | ...
|
| Furniture and household utensils
| 60 | 444 | ...
|
| Clothing and footwear
| 84 | 860 | ...
|
| Medical care
| 23 | 312 | ...
|
| Transport and communication
| 36 | 1185 | ...
|
| Education
| 13 | 466 | ...
|
| Reading and recreation
| 69 | 1115 | ...
|
| Miscellaneous
| 32 | 446 | ...
|
| Total
| 561 | 10000 | 230000
|
Household consumption expenditure
Consumption expenditure for the purpose of the index relates to
disbursements for purchasing goods and services necessary for
daily life and includes imputed rental values for owner-occupied
housing. It excludes income tax, life insurance, social security
payments, savings, securities, remittances, gifts, religious
contributions and other non-consumption items.
Method of data collection
Prices for most items are collected through personal visits to
selected outlets and service establishments in 167 cities, towns
and villages. Official tariffs are used for items such as transport
and postal services. Prices are surveyed on Wednesday, Thursday
or Friday of the week which includes the 12th of each month.
However, for 42 items of fresh fish, fresh vegetables
and fresh fruit, prices are collected three times a month.
Education fees are surveyed in April and September. The prices
used in the index are the retail prices actually paid by
consumers on the pricing day. Low prices due to bargain,
clearance and discount sales, temporary abnormal prices, reduced
prices for quantity purchases and prices of second-hand
articles, etc., are excluded.
Housing
Rent quotations relate to privately owned houses and rooms and
publicly owned houses. Data on rents of publicly owned houses
are supplied each month by the agency managing them. Rent quotations
for private houses are obtained according to structure and
floor space through a survey conducted each month, covering all
households in privately rented houses in the sampled districts.
The rental equivalence approach (imputed rent) is used for
the housing cost for owner-occupied dwellings.
Specification of varieties
Specifications of varieties are given in detail according to such
characteristics as size, quality, brand and accessories so that
the same items are constantly surveyed every month.
Substitution, quality change, etc.
If a selected product is no longer available for pricing, a
product similar to the original is substituted. When the old and
the new products are identical, the method of direct linking is
used. Otherwise, adjustments are made to the prices to take into
account differences in volume or quality.
Seasonal items
The sub-group weights for seasonal items (i.e. fresh fish, fresh
vegetables and fresh fruit) are fixed throughout the year. Each
item in this sub-group is given the weight according to its
relative importance which varies from month to month. The average
prices for the latest on-season period are used for seasonal items
other than fresh food during the off season.
Computation
The index is computed according to the Laspeyres formula as a weighted
arithmetic average with fixed base, using weights corresponding to the
base period.
Price relatives by item for each municipality are calculated and then
averaged with the respective weights for each municipality, and average
price relatives by items for the whole country are obtained. The
average price relatives for the whole country are averaged with the
respective item weights to obtain sub-group indexes. Major group
indexes and the general index are calculated in a similar way from the
sub-group index by using the respective group weights.
Other information
A General index
, Ten major group index
and Sub-group
index
are compiled for 72 areas, i.e. the whole country,
eight city groups, ten districts, four metropolitan areas, 47
cities with prefectural government, Kawasaki-shi and
Kitakyushu-shi.
Commodity and service group index
and Index by items
are
compiled for the whole country and Ku-area of Tokyo. Index by
types of households
, Index by characteristics of items
and
Index computed by chain index method
are compiled for the whole
country.
Organisation and publication
Management and Coordination Agency, Statistics Bureau: Monthly
Report on the Consumer Price Index
.
Idem: Annual Report on the Consumer Price Index
.