U.S. Bureau of Labor Statistics,
Producer Price Indexes, monthly.
For more information:
http://www.bls.gov/ppi/
Producer price indexes (PPI) measure average changes in
prices received by domestic producers of commodities in all
stages of processing. Most of the information used in
calculating the indexes is obtained through the systematic
sampling of nearly every industry in the manufacturing and
mining sectors of the economy. The PPI program also includes
some information from other sectors—agriculture, fishing,
forestry, services, and gas and electricity. Because
producer price indexes are designed to measure only the
change in prices received for the output of domestic
industries, imports are not included. The sample currently
contains about 3,200 commodities and 80,000 quotations per
month.
There are three primary systems of indexes within the
PPI program: (1) Stage of processing indexes; (2) commodity
indexes; and (3) indexes for the net output of industries
and their products. The stage-of-processing structure
(tables 1 and 2) organizes products by class of buyer and
degree of processing. The commodity structure (tables 2 and
3) organizes products by similarity of end-use or material
composition. The entire output of various industries is
sampled to derive price indexes for the net output of
industries and their products (table 4).
Within the stage-of-processing system, finished goods
are commodities that will not undergo further processing and
are ready for sale to the final demand user, either an
individual consumer or business firm. Consumer foods include
unprocessed foods such as eggs and fresh vegetables, as well
as processed foods such as bakery products and meats. Other
finished consumer goods include durable goods such as
automobiles, household furniture, and appliances, and
nondurable goods such as apparel and home heating oil.
Capital equipment includes producer durable goods such as
heavy motor trucks, tractors, and machine tools.
The stage-of-processing category for intermediate
materials, supplies, and components consists partly of
commodities that have been processed but require further
processing. Examples of such semifinished goods include
flour, cotton yarn, steel mill products, and lumber. The
intermediate goods category also encompasses nondurable,
physically complete items purchased by business firms as
inputs for their operations. Examples include diesel fuel,
belts and belting, paper boxes, and fertilizers.
Crude materials for further processing are products
entering the market for the first time that have not been
manufactured or fabricated and that are not sold directly to
consumers. Crude foodstuffs and feedstuffs include items
such as grains and livestock. Examples of crude nonfood
materials include raw cotton, crude petroleum, coal, hides
and skins, and iron and steel scrap.
Producer price indexes for the net output of industries
and their products are grouped according to the North American
Industrial Classification System (NAICS) and the Census product code
extension of the NAICS. Industry price indexes are compatible
with other economic time series organized by NAICS codes, such
as data on employment, wages, and productivity. Table 4
lists indexes for the net output of major mining and
manufacturing industry groups at the 3-digit level.
Producer price indexes are based on selling prices
reported by establishments of all sizes selected by
probability sampling, with the probability of selection
proportionate to size. Individual items and transaction
terms from these firms are also chosen by probability
proportionate to size. BLS strongly encourages cooperating
companies to supply actual transaction prices at the time of
shipment to minimize the use of list prices. Prices are
normally reported by mail questionnaire for the Tuesday of
the week containing the 13th.
Price data are provided on a voluntary and confidential
basis; no one but sworn BLS employees are allowed access to
individual company price reports. All producer price indexes
are routinely subject to revision once, 4 months after
original publication, to reflect the availability of late
reports and corrections by respondents.
Net output values of shipments are used as weights for
industry indexes. Net output values refer to the value of
shipments from establishments in one industry to
establishments classified in another industry. However,
weights for commodity price indexes are based on gross
shipment values, including shipment values between
establishments within the same industry. As a result, broad
commodity grouping indexes such as the all commodities index
are affected by the multiple counting of price change at
successive stages of processing, which can lead to
exaggerated or misleading signals about inflation. Stage-of-
processing indexes partially correct this defect, but
industry indexes consistently correct for this at all levels
of aggregation. Therefore, industry and stage-of-processing
indexes are more appropriate than broad commodity groupings
for economic analysis of general price trends.
Weights for most traditional commodity groupings of the
PPI, as well as all indexes (such as stage-of-processing
indexes) calculated from traditional commodity groupings,
currently reflect 1997 values of shipments as reported in
the Census of Manufactures and other sources.
Industry indexes shown in table 4 are also now
calculated with 1997 net output weights.
Effective with publication of January 1988 data, many
important PPI series (including stage-of-processing
groupings and most commodity groups and individual items)
were placed on a new reference base, 1982=100, to coincide
with the reference year of the shipment weights. From 1971
through 1987, the standard reference base for most PPI
series was 1967=100. Except for rounding differences, the
shift to the new reference base did not alter any changes to
previously published percent changes for affected PPI
series. (See “Calculating Index Changes,” below.) The new
reference base is not used for indexes with a base later
than December 1981, nor for indexes for the net output of
industries and their products.
For further information on the underlying concepts and
methodology of the Producer Price Index, see chapter 14,
“Producer Prices,” in BLS Handbook of Methods (September
1992), Bulletin 2414, updated September 2003 at:
http://www.bls.gov/opub/hom/homch14_itc.htm.
Reprints are available from the Bureau of Labor Statistics on request.
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referenced on dataset section Notes (#2)
