In
1985
, the compilation of WPI has been improved by way of reclassification of
commodities with a view to better analyze trend of prices. It has therefore been renamed as the
Producer Price Index (PPI) according to the United States system of classification. These
indexes would enable various user to monitor changes in prices from production stage to primary
markets and using
1985
as the base year
(1985 = 100).
The prices are used in calculating PPI under the stage of processing have obtained to a
large extent from the first commercial transaction prices. These representative prices are taken
from the producers, central markets, local markets, trade associations as well as from other
government agencies.
In
1999
, the Producer Price Index calculation has been improved the listing, weight, and
base year from
1985
to
1995
by using the input - output table conducted by the Office of the
National Economic and Social Development Board. The former Wholesale Price Index has been
renamed as the new Producer Price Index for Thailand under the classification of products by
activities (CPA) in order to compare with the international classification. The price used in the PPI
calculation are at producer level or nearly. In
2004
, PPI calculation has been changed the listing,
weight, and base year from
1995
to
2000 (2000 = 100).
