| The Data: Coverage, Periodicity, and Timeliness |
| Coverage characteristics | 5.1.1 Statistical presentation - The Wholesale Price Index (WPI) is a Laspeyres index（2016=100）, measuring the average changes of selling prices received by producers for their outputs, such as raw materials, semi-finished products and finished products. The WPI comprises the Domestic Wholesale Price Index (DWPI), Import Price Index (IPI) and Export Price Index (EPI).
- The WPI covers 1,195 items: DWPI covers 596 items, IPI covers 304 items and EPI covers 295 items. Most of the prices are collected through a monthly mail survey or Internet Reporting System. The designated companies report the actual selling prices of selected commodities with the same specifications (in principle, price after adjustment for rebate, tax, shipment, etc.) around the 20th of each month.
- The weights of DWPI manufacturers are obtained from the Industrial Production Statistics, National Income Statistics and data provided by relative associations that are gathered in 2019. For non-manufacturers (Agriculture, Forestry, Fishing, Water Supply, etc.), the weights are referred to the Year books of Agriculture, Forestry, Fishing, Water Supply and Electricity. The weights of IPI and EPI are based on the customs-clearing values of import goods of 2019 in Taiwan Area, including re-imports. The values of import (export) items not sampled are being added proportionally to that of surveyed items similar in attributes and price trends.
- The indices as a whole are normally re-based about five years and the weights are changed every 2-3 years.
- Seasonally adjusted and unadjusted indices are provided.
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| Periodicity | 4.1.1 Periodicity Monthly |
| Timeliness | 4.1.2 Timeliness Around the fifth working day (subject to postponement due to Chinese Lunar New Year or other consecutive public holidays) after the end of the reference month. |
| Access by the Public |
| Advance dissemination of release calendar | 5.1.3 Advance release calendar - In principle, the press release is made around the fifth working day (subject to postponement due to Lunar New Year or other consecutive national holidays) after the end of the reference month. The date of the next release is announced in each news release.
- A schedule of the precise release dates for the Calendar year is listed on the website:
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| Access by the Public |
| Simultaneous release to all interested parties | 5.1.4 Simultaneous release |
| Integrity |
| Dissemination of terms and conditions under which official statistics are produced, including Confidentiality of individual responses | 0.1.1 Responsibility for collecting, processing, and disseminating statistics - All statistics collected, compiled and published by the DGBAS are governed by the Statistics Act and the Enforcement Rules.
- The data on the price indices are disseminated by the DGBAS as a service to the public.
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| Identification of internal government access to data before release | 1.2.2 Internal governmental access to statistics prior to release The information published in the press release and advance copies of the WPI news release are provided to the President, the Premier, the Vice Premier and the Governor of Central Bank of the R.O.C before official release. |
| Identification of ministerial commentary on the occasion of statistical releases | 1.2.3 Attribution of statistical products No ministerial commentary is released with these data. Department of Statistics, DGBAS, Executive Yuan provides its own analytical commentary with these data releases. |
| Provision of information about revision and advance notice of major changes in methodology | 4.3.1 Revision schedule - All seasonally adjusted and unadjusted WPIs are routinely subject to revision for up to 3 months after preliminary publication. Indices are revised to reflect late reports and corrections received from respondents. A final estimate will be issued in 3 months after initial publication. Besides, the seasonally adjusted monthly data from 2013 to last year are revised at the time of the release of the April WPI.
- Major program changes are made on WPI re-basing every 2-3 years. As soon as the re-basing process is finished, the new results are announced in the upcoming February with data of January.
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| Quality |
| Dissemination of documentation on methodology and sources used in preparing statistics | 5.2.1 Dissemination of documentation on concepts, scope, classifications, basis of recording, data sources, and statistical techniques Detailed methodological document can be obtained on the website https://ws.dgbas.gov.tw/001/Upload/467/relfile/11691/2043/wpi_description.pdf |
| Dissemination of that support statistical cross-checks and provide assurance of reasonableness | 4.2.2 Temporal consistency - The “Price Index” news release publishes a monthly analysis of price movements and summary tables on the WPI.
- The e-book “ Price Statistics Monthly” is made available immediately at the time of release.
- The WPI is further broken down into (a) basic group; (b) indices by waygoing and by origins; (c) indices for domestic sales by basic group; (d) indices for domestic sales by stage of processing; (e) time series of WPI.
- The IPI is further broken down into (a) basic group; (b) Indices by usage; (c) time series of IPI.
- The EPI is further broken down into (a) basic group; (b) Indices by usage; (c) time series of EPI.
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