Calculation of producers’ price index of industrial products from imports

Statistical Office of the Republic of Serbia

Price statistics department

Ana Zivkovic

Statistician analyst

5 Milana Rakića, Belgrade

ana.zivkovic@stat.gov.rs

+381 11 2412922, ext. 231

The subject of this research is import prices of  producers of industrial products.

The objective of the survey is to calculate, according to collected prices and respective weights, producer price indices of industrial products from imports. Indices are regarded as indicators of dynamics of import prices of producers of industrial products.

NACE Rev. 2

Sections B to C 29 except: 05, 07, 09 and 18.

Enterprises with an annual turnover below 1.5 million EUR are not included in the reference population.

Import prices are actual transaction prices (c.i.f.) for products which importers buy in largest quantities, excluding all duties and taxes, as far as possible on the 15th in the month.

Observation units are industrial and trading enterprises and their products. Reporting unit is enterprise.

Import prices are followed for over 280 products, classified into sections B and C, 22 divisions, from about 120 enterprises on the territory of the Republic of Serbia.

Republic of Serbia. Starting from 1999 the Statistical Office of the Republic of Serbia has not at disposal and may not provide available certain data relative to Kosovo and Metohia and therefore these data are not included in the coverage for the Republic of Serbia (total). 

Import price indexes are calculated from 2017.

Base (reference) year: previous year.

Indices.

Monthly.

National legislation:

SORS is the only institution in the country engaged in the production of the IMPI.

IMPI`s data are available to the users on the SORS website.

IMPI`s data are transmitted to Eurostat through eDAMIS.

Data confidentiality is stipulated by:

- Official Statistics Law (Official Gazette of RS, number 104/2009), Articles 44, 45, 46, 47, 48, and 49.

(www.stat.gov.rs/media/2322/zakon_o_statisticie.pdf)

- Rulebook on statistical data protection in the Statistical Office of the Republic of Serbia

(www.stat.gov.rs/media/2343/rulebook-on-statistical-data-protection-in-sors.doc ) 

- Guidelines on measures of data and information protection in the Statistical Office of the Republic of Serbia

(www.stat.gov.rs/media/2341/guidelines-on-measures-of-data-and-information-protection-in-the-sors.doc )

In order to protect individual's information privacy and business interests of business units, only aggregated data are published (observation units are not recognizable either directly or indirectly). Therefore, adjusted contents of the tables are in use and certain rules are applied to protect data, such as a threshold minimum number of units (Official Statistics Law (Official gazette RS, no 104/09).

Calendar of releases is available at SORS website on the 1st day of December every year for the forthcoming year (http://www.stat.gov.rs/en-US/calendar).

Calendar of releases is available at SORS website:

http://www.stat.gov.rs/en-US/calendar

The data obtained through statistical surveys are released at the internet presentation (http://www.stat.gov.rs/en-US/),

Monthly.

Statistical release IMPI is published on the SORS website, at 12:00 (local time), 10 days after the end of the reference month, in Serbian as well as in English language.

SORS  complex publications:

• Monthly statistical bulletin.
• Statistical pocketbook of Serbia.
• Statistical Yearbook of the Republic of Serbia.

IMPI`s data are posted on the SORS website: http://www.stat.gov.rs

On request, the access to anonymized microdata is ensured to scientific and research institutions.

Current data are sent monthly to Eurostat via eDamis.

Detailed methodological explanations are available on the website of the Statistical Office of the Republic of Serbia:

http://www.stat.gov.rs/en-US/istrazivanja/referentni-metapodaci

Not applicable.

Not applicable.

IMPI`s data primarily are used as follows:

•        economic indicators (National Bank, Ministries and other representatives of  government),

•        deflators of time series, especially for the needs of national accounts.

•        tools for price harmonization when conducting various sales and purchase agreements.

On biennial basis (once in two years), by the means of web interview, implemented is the User Satisfaction Survey. The survey results are available at SORS website: http://www.stat.gov.rs/en-US/o-nama/sistem-upravljanja-kvalitetom.

IMPI`s are covering sections B to C 29 according NACE Rev. 2.

The products for price monitoring are selected from each industrial division, with the highest imports on the domestic market and their prices can represent the general price trends in the industry by division and according to products destination (MIGs). When creating the list, the selected products should represent the fluctuations of prices also for the products not included in the list.

Sampling error cannot be calculated because the methodology of price statistics based on the principle of representativeness. Primarily are selected enterprise by greatest production and realization of selected products.

Response rate is over 90%. Enterprises in terms of their size or representativeness are contacted by phone in order to have the data on time. Price for temporarily missing product is processed by repeating the last reported price. In cases when an enterprise cease to import a product of the quality for which the prices were reported then a new quality shall be defined for the product with the largest import and that is anticipated to be imported for a long time and in large quantities. For the new selected quality of a product, the prices are given simultaneously for the current and the previous month, and in reports stated are always the prices for the same quality of a product. Enterprises shall be obliged to explain any quality change.

The reporting period is the month. Enterprises complete reports with the prices as far as possible on the 15th in referent month and forward them to the respective statistical authorities until the 28th day of the subject month.

IMPI`s are published each month about 10<sup>th</sup> and relate to the previous month in the edition Statistical Release with the mark CN23 and they are presented on the website of the Statistical Office of the Republic of Serbia (www.stat.gov.rs). An exception is only the month January when, due transit to a new year and the methodology changes in indices related to that, data are published  28<sup>nd</sup> February. First data for IMPI`s are also final data, and are not corrected at a later stage.

Statistical releases for IMPI`s are published each month according to the announced release calendar.

IMPI`s are calculated for the whole country and the representativeness and the comparability of the indicators across countries is good.

IMPI`s are calculated from the January of 2017.

There is no other statistical output for comparison. In import price statistics we use data from foreign trade statistics for designe sample frame and for calculating weights.

Aggregates at higher level are consistent with their sub-aggregates on lower level.

Not applicable.

Major changes in methodology are announced in advance or at the time of data dissemination.

Product/Item selection:

Since the methodology of price statistics is based on the principle of representation, import prices in industry are followed for a certain number of import units, being reporting units at the same time. Primarily selected are enterprises featuring large import volume of respective products.

For each industry division created is a separate list of products, the prices of which shall be followed. The products of a division are classified into a number of groups, classes and subclasses, and for them reliable data on fluctuations of prices shall be provided. When creating the list, the selected products should represent the fluctuations of prices also for the products not included in the list. Therefore, important is the contents of every group, class and subclass of products. Included are the products with the largest share in the overall import. The number of representative items in classes and subclasses depends upon classes’ homogeneity. As a rule, homogenous classes require a smaller number of representative items than less homogenous ones, since the price variations in homogenous classes are smaller. Each selected product shall be specified as much as possible and this shall ensure the comparability of prices of the products of the same quality. The products with decreased import or those discontinued shall be replaced with other products of the same class that have the largest import.

Every year the list of products shall be analyzed and updated when required. Larger changes, i.e. the revision of the list of products are carried out every fifth year, when the weights are also changed.

Sources of weights:

The purpose of index weighting is that each product is represented according to its share in total import and thereby group/class index shall be representative as a synthetic indicator of complex phenomena. The weights used for group/class indices of producer prices of industrial products are calculated according to the data of regular statistical surveys. Firstly the weights for all divisions are calculated, and then the weights for each product within a division. Weights of divisions actually represent the share of any industrial division in the total value of annual import. Weights of sections and subsections are obtained as the sum of the weights of the respective industrial divisions.

Weights for products within a division are calculated according to the data of external trade statistics on annual value of imports according to the CA, for the products imported. The import coverage within certain division is full, regardless the number of the selected products within the division. The import value of the non-covered products is added to the import value of the selected products and therefore the sum of values the selected products within a division represents the actual import of the division. In this way, the weighting system fully complies with the representation principles.

Weights are changed (calculated) every fifth year and this is in accordance with international recommendations and practice. The current weights have been applied since 2017 and they were calculated according to the data for 2015. 

Monthly

The data on import prices in industry are provided by enterprises using C41U questionnaire. Enterprises complete reports with the prices as far as possible on the 15th in referent month and forward them to the respective statistical authorities until the 28th day of the subject month.

All data collection is done by postal questionnaires (sending for each month separately). Data collection via Internet (Web questionnaires) is planed in the nearest future.

The staff of the Price Statistics Division performs checking of prices on questionnaires and control of data entry by comparing calculated monthly indices between the current and the previous month and clarifies all significant changes with reporting units via the telephone and e-mail.

After the receipt of reports on prices (deadline: 28th day in a month), the data checkup and their entry are carried out. Price for temporarily missing product is processed by repeating the last reported price. Correction of prices in case of quality changes is also done if necessary.

Import price indices are calculated for certain products (individual indices), for groups/classes (group/class indices) and for all products included in the index list (total index). Import prices are used for the calculations of individual indices, while group/class indices are calculated by weighting individual indices. For the purpose of this survey, average import price for previous year is used as the base.

Aggregated (i.e. group/class) indices are calculated by weighting individual indices according to Laspeyres formula, which is applied in our price statistics for calculating the indices of import prices in industry:

where:

P_n      = product price in current month,

P₀      = product price in base period,

W₀     = value of sold quantities in base period.

Prices quoted in other currencies are converted into the national currency using the exchange rate of the reference date (15th of each month).

No seasonal adjustments are made.

None