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PRESS RELEASE

PRESS RELEASE

TECHNICAL INFO:
ŞEYDA ŞATIR EGEMEN
INFO REQUEST:
Data Dissemination Group
+90 312 454 75 04    
+90 312 454 72 65
seyda.satir@tuik.gov.tr
bilgi@tuik.gov.tr
  /tuikbilgi
/tuikbilgi
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Data sources: VAT and SCT declarations obtained from the Revenue Administration are used as the data source for the compiling of turnover indices.

Method of weighting:  Not available
Impact and contribution analysis: Impact and contribution analysis are done on enterprise basis by sectors.

Imputation:  Incorrect data or outliers  in administrative records are corrected by statistical methods. No imputation is done for non-respondence.

Index type: A simple index is used which is calculated by dividing the relevant levels by the base year averages.

For the industrial sector, the index is calculated and published in domestic, non domestic and total detail.

No distinction for domestic and non domestic exists for construction and trade and services sectors, only total turnover is calculated.

Base year: 2015
Data compilation: VAT and SCT declarations are compiled monthly from Revenue Administration.
Purpose: Turnover is an important short term indicator used in the assessment of the economic situation in our country. Turnover Indices are calculated to follow the changes of this concept which is composed of sales of goods and services invoiced by the enterprise in the reference month over time, to monitor the development in quarterly and yearly basis, to have data consistent with the European Union regulations, to ensure the possibility of international comparisons and to form a resource for various researches for the turnover of the enterprises.
 
Coverage:  All the enterprises which give VAT declaration to the Revenue Administration are included in the index calculation.

Classifications: The indices are calculated according to the NACE Rev. 2 economic activity classification and Main Industrial Groupings (MIG’s).
Geographical coverage: The whole country (Turkey) is covered.
Economic activity coverage: Following sectors are covered while calculating Turnover Indices according to Nace Rev.2;
SECTION B - MINING AND QUARRYING
SECTION C - MANUFACTURING
SECTION F - CONSTRUCTION
SECTION G - WHOLESALE AND RETAİL TRADE; REPAİR OF MOTOR VEHİCLES AND MOTORCYCLES
SECTION H - TRANSPORTATİON AND STORAGE
SECTION I - ACCOMMODATİON AND FOOD SERVİCE ACTİVİTİES
SECTION J - INFORMATİON AND COMMUNİCATİON
SECTION L - REAL ESTATE ACTİVİTİES
SECTION M - PROFESSİONAL, SCİENTİFİC AND TECHNİCAL ACTİVİTİES
SECTION N - ADMİNİSTRATİVE AND SUPPORT SERVİCE ACTİVİTİES
 
Non-covered sectors: 09 "Mining Support Service Activities" are not published but are included in the aggregated indices.
 
Reference period and periodicity: The reference period is the period until the last day of each month on the first day and the frequency of the survey is monthly. 

 
The Revision Information Form regarding the revisions to be carried out in the current year for the statistics produced in the scope of this press release can be accessed from the link below.
 


http://www.turkstat.gov.tr/indir/revizyon/2020_RBF_EN_KDIIDB_CHGG_CE.pdf
Seasonal Adjustment

Seasonal and calendar related effects prevent observing the general tendency of data because of their temporary characteristics. Therefore, identification of seasonal patterns of short term indicators plays crucial role in order to make reliable comparisons between consecutive periods. 

Method Used

The seasonal adjustment of Turnover Indices is carried out using TRAMO-SEATS methodology. The software that is used for the application of this method is JDemetra+ developed by the National Bank of Belgium (NBB) in cooperation with the Deutsche Bundesbank and Eurostat in accordance with the Guidelines of the European Statistical System.

Process of the seasonal adjustment

Seasonal and calendar adjustment process of Turnover Indices begins at the end of each year with the identification of the models of next year.  This specified model structure is kept fixed throughout the year to adjust seasonally and/or calendar effects. At the end of the year, just like the previous year, specification of econometric estimation models for the following year is done. The identified process repeats itself in a cyclical manner each year.

While 199 subtitles of Turnover Indices contain both seasonal and calendar effects,   14 subtitles contain only calendar effects, 32 subtitles contain only seasonal effects and 13 subtitles contain neither of these effects.

Direct or indirect seasonal adjustment

Seasonally and calendar adjusted figures of Turnover Indices are produced by indirect approach. Firstly the three digit NACE Rev2 classification individual subseries of Turnover Indices are seasonally adjusted and then aggregated to derive seasonally and calendar adjusted totals. The advantages of indirect approach are calculation of contributions to growth from components of main aggregates and retaining additivity.

Revision Policy

Seasonal adjustment procedure is subject to revisions over time because of the re-estimation of seasonal component as new observations are added. These revisions are implemented on the data of the last three years excluding the current year.



Adjusted data is published in 3 different ways.
  • “Calendar adjusted” data is derived from unadjusted data by removing calendar and holiday originated effects. Calendar adjusted data should be used in comparisons regarding the same month/period of the previous year.
  • “Seasonally adjusted” data is derived from unadjusted data by removing effects originating from seasonal effects. Seasonally adjusted data should be used in comparisons regarding the previous month/period.
  • If unadjusted data contains both calendar and holiday, and seasonal effects, “seasonally and calendar adjusted” data is derived by removing these effects. Seasonally and calendar adjusted data should be used in comparisons regarding the previous month/period