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Stock and Supply Short-term Survey

• 1Contact
  • 1.1Contact organisation
    National Statistics Institute of Spain
    
  • 1.5Contact mail address

    Avenida de Manoteras 50-52 - 28050 Madrid

    
    
• 2Metadata update
  • 2.1Metadata last certified
    04/06/2024
  • 2.2Metadata last posted
    01/03/2024
  • 2.3Metadata last update
    04/06/2024
• 3Statistical presentation
  • 3.1Data description

    The Short-term Stock and Inventory Survey has two objectives. On the one hand, it aims to provide the necessary information to obtain a short-term indicator that measures the evolution of the value of inventory levels in the short term and, on the other hand, to supply information on changes in inventory levels as an input for National Accounts.

    It is a statistic with direct data collection.

    Value indices are published in which the information is presented in current terms (nominal), that is, without adjusting the effects on price variations in them, calculated as chain-linked indices using 2015 as the base period.

    Currently, the monthly and quarterly indices on inventory levels are published quarterly.

  • 3.2Classification system
    • Clasificaciones utilizadas

      Bearing in mind the economic unit's main activity, classified and coded according to the National Classification of Economic Activity NACE Rev.2, indicators are obtained for:

      
      
      

      
      
      • Section G: ‘Wholesale and retail trade; repair of motor vehicles and motorcycles’ except group 46.1: ‘Wholesale on a fee or contract basis’ and their breakdown by division (two digits of the NACE Rev.2), that is to say:
        
        
        
        • Division 45: ‘Wholesale and retail trade and repair of motor vehicles and motorcycles’.
        
        
        • Division 46: ‘Wholesale trade, except of motor vehicles and motorcycles’ excluding group 46.1: ‘Wholesale on a fee or contract basis’.
        
        
        • Division 47: ‘Retail trade, except of motor vehicles and motorcycles’.
        
        
        
        
      
      
  • 3.3Sector coverage

    The Short-term Stock and Inventory Survey studies the population made up of economic units (companies) whose main activity, coded according to the National Classification of Economic Activity NACE Rev.2 , is included in the sections:

    • G: ‘Wholesale and retail trade; repair of motor vehicles and motorcycles’ excluding group 46.1: ‘Wholesale on a fee or contract basis’.
  • 3.4Statistical concepts and definitions
    • Company
      The company is the smallest combination of legal units that is an organizational unit producing goods or
      services, which benefits from a certain degree of autonomy in decision-making, especially for the
      allocation of its current resources. A company carries out one or more activities at one or more
      locations. A company may be a sole legal unit.
    • Establishment or Local Unit
      Establishment or Local Unit is the productive unit located in a topographically marked place (workshop, mine, factory, etc.), from which economic activities are carried out by one or more persons from the same company.
      
      The establishment or Local Unit is the observation or information unit, that is, the unit chosen from the directory and to which the questionnaire data is to refer
    • Product stocks
      Inventories of goods or services that comprise:
      - Work in progress: Goods or services being formed or transformed in an activity centre.
      - Semi-finished goods: Products manufactured by the company and not normally sold until they are subject to further preparation, incorporation or transformation.
      - Finished goods: Goods manufactured by the company for use by end consumers or by other companies.
      - By-products: Secondary or incidental products resulting from primary manufacturing.
      - Waste: Materials inevitably obtained in conjunction with products and by-products, providing they have intrinsic value and can be used or sold.
      - Recovered materials: Materials which, on the basis of their intrinsic value, are returned to storage after having been used in the production process.
    • Production cost
      The production cost shall comprise the purchase price of raw materials and consumables, directly related costs and the proportional amount of costs indirectly attributable to the related products, insofar as these relate to the production, construction or manufacturing period, are required to bring the item into a saleable condition and are based on the level of usage of normal production capacity.
    • Purchase price
      The purchase price comprises the amount invoiced by the seller, after deduction of any discounts, rebates or other similar items, such as interest incorporated into the nominal amount, plus any additional costs incurred to bring the goods to a saleable condition, such as transport, import duties, insurance and other costs directly attributable to the acquisition of inventories.
      
      Nevertheless, the purchase price can include interest on payables maturing within one year which do not have a contractual interest rate when the effect of not discounting the cash flows is immaterial.
    • Stock of goods for resale
      Goods acquired by the company and intended for sale without any further transformation.
    • Stock of other supplies
      Inventories that without being goods for resale or raw materials comprise the following assets:
      - Components: These are the ones normally manufactured outside the company and acquired by the company for incorporation in production, with no further transformation.
      - Fuel: Storable materials for providing energy.
      - Spare parts: Parts to be assembled as part of installations, equipment or machines in substitution of other
      similar parts including spare parts that are stored for less than one year.
      - Sundry materials: Other consumable materials that will not be incorporated into the finished product.
      - Packaging: Covers, casings and wrappings, generally not recoverable, used to protect products or merchandise during transit.
      - Containers: Receptacles or vessels normally sold along with the product contained therein.
      - Office supplies: Supplies used in offices, except where the company opts to consider that office materials acquired during the reporting period are used within that same period.
    • Stock of raw materials
      Materials that will form part of manufactured goods after appropriate preparation or transformation.
  • 3.5Statistical unit

    For economic units included in the target population whose main activity falls under the activities in section C of the NACE Rev.2, the establishment is used as a statistical unit (see the definition in section 3.4). Although, in general, the reporting unit is also the establishment, there are cases in which the company is the unit that provides information for all the establishments that it includes.

    For the economic units included in the target population whose main activity is included in the activities of section G of the NACE Rev.2, the company is used as the statistical unit and the reporting unit (see the definition in section 3.4).

  • 3.6Statistical population

    The target population of the study is made up of the economic units whose main activity, classified according to NACE Rev.2, is included in Section G: ‘Wholesale and retail trade; repair of motor vehicles and motorcycles’ except group 46.1: ‘Wholesale on a fee or contract basis’.

  • 3.7Reference area

    The geographic scope is made up of the entire national territory except Ceuta and Melilla. However, for statistical units whose main activity belongs to division 47 of the NACE Rev.2: ‘Retail trade, except for motor vehicles and motorcycles’ the aforementioned Autonomous Cities are also included.

  • 3.8Time coverage

    The monthly data needed to prepare this statistical operation begin to be collected in the reference month corresponding to January 2013. The Short-term Stock and Inventory Survey was first published in December 2015, with 2010 being the base year at that time.

    Currently, the base year is 2015, as the average of the indices of that year are equal to 100. The first publication with base year 2015 was published on 10 October 2018.

  • 3.9Base period

    Indices corresponding to the base of 2015 began to be published in 2018.

    The Short-term Stock and Inventory Survey uses chain-linked indices in a way that:

    • The base period is that in which the average of the year's indices equals 100. The base period is 2015.
    • The reference period of the variable is the period whose values are comparable to the inventory variables of the reference month. The reference period for 2024 is December 2023.
    • The reference period for weightings is that to which the weightings that serve as a structure for the system refer. The reference period of the weightings for 2024 is December 2023.
• 4Unit of measure
  • 4.1Unit of measure

    Value indices and their monthly, quarterly, annual variation and year-to-date average rates.

• 5Reference period
  • 5.1Reference period

    The reference period of the inventory level is the last day of the month.

    Data referred to the period: Trimestral A: 2023 TRI: IV

• 6Institutional mandate
  • 6.1Legal acts and other agreements

    The compilation and dissemination of the data are governed by the Statistical Law No. 12/1989 "Public Statistical Function" of May 9, 1989, and Law No. 4/1990 of June 29 on “National Budget of State for the year 1990" amended by Law No. 13/1996 "Fiscal, administrative and social measures" of December 30, 1996, makes compulsory all statistics included in the National Statistics Plan. The National Statistical Plan 2009-2012 was approved by the Royal Decree 1663/2008. It contains the statistics that must be developed in the four year period by the State General Administration's services or any other entity dependent on it. All statistics included in the National Statistics Plan are statistics for state purposes and are obligatory. The National Statistics Plan 2021-2024, approved by Royal Decree 1110/2020, of 15  December, is the Plan currently implemented. This statistical operation has governmental purposes, and it is included in the National Statistics Plan 2021-2024. (Statistics of the State Administration).

    
    

    The Short-term Stock and Inventory Survey was favourably judged, on 26 June 2013, by the Permanent Commission of the Higher Statistical Council, the advisory body of the state statistical services and for the social involvement of respondents, producers and users of official statistics.

  • 6.2Data sharing
    The exchanges of information needed to elaborate statistics between the INE and the rest of the State statistical offices (Ministerial Departments, independent bodies and administrative bodies depending on the State General Administration), or between these offices and the Autonomic statistical offices, are regulated in the LFEP (Law of the Public Statistic Function). This law also regulates the mechanisms of statistical coordination, and concludes cooperation agreements between the different offices when necessary.
    
• 7Confidentiality
  • 7.1Confidentiality - policy

    The Statistical Law No. 12/1989 specifies that the INE cannot publish, or make otherwise available, individual data or statistics that would enable the identification of data for any individual person or entity. Regulation (EC) No 223/2009 on European statistics stipulates the need to establish common principles and guidelines ensuring the confidentiality of data used for the production of European statistics and the access to those confidential data with due account for technical developments and the requirements of users in a democratic society

    
    
  • 7.2Confidentiality - data treatment
    INE provides information on the protection of confidentiality at all stages of the statistical process: INE questionnaires for the operations in the national statistical plan include a legal clause protecting data under statistical confidentiality. Notices prior to data collection announcing a statistical operation notify respondents that data are subject to statistical confidentiality at all stages. For data processing, INE employees have available the INE data protection handbook, which specifies the steps that should be taken at each stage of processing to ensure reporting units' individual data are protected. The microdata files provided to users are anonymised.
    

    The Short-term Stock and Inventory Survey is a statistical operation included within the National Statistics Plan which is subject, therefore, to Law 12/1989, of 9 May, on the Public Statistical Function and, consequently, its data are protected by statistical secrecy in all stages of preparation.

    All statistical staff have the obligation to maintain this statistical secrecy (art. 17.1 of the Public Statistical Function Law). In the specific case of this survey, only aggregated information is released.

• 8Release policy
  • 8.1Release calendar

    The advance release calendar that shows the precise release dates for the coming year is disseminated in the last quarter of each year.

    
    
  • 8.2Release calendar access

    The calendar is disseminated on the INEs Internet website (Publications Calendar)

    
    
  • 8.3User access

    The data are released simultaneously according to the advance release calendar to all interested parties by issuing the press release. At the same time, the data are posted on the INE's Internet website (www.ine.es/en) almost immediately after the press release is issued. Also some predefined tailor-made requests are sent to registered users. Some users could receive partial information under embargo as it is publicly described in the European Statistics Code of Practice

    
    
• 9Frequency of dissemination
  • 9.1Frequency of dissemination

    The indices corresponding to the Short-term Stock and Inventory Survey are published quarterly.

• 10Accessibility and clarity
  • 10.1News release

    The results of the statistical operations are normally disseminated by using press releases that can be accessed via both the corresponding menu and the Press Releases Section in the web

    
    
  • 10.2Publications

    Information related to this indicator is published on the INE website. The following publications and information can be found on said website:

    • Press release, which highlights the aspects that most influence the evolution of the indicator in the reference period.
    • Table annex, which contains the tables annexed to the press release.
    • Methodology, where the standardised methodological report, the file in the inventory of statistical operations and the general methodology of the Short-term Stock and Inventory Survey can be accessed.
    • Related links, as well as providing access to statistical operations whose questionnaires collect short-term information on inventories (SSAI, RTI and ITI-INORI), provide access to the results and weightings published in the previous base (2010).

    All this information and these publications can be found at this link.

  • 10.3On-line database

    INEbase is the system the INE uses to store statistical information on the Internet. It contains all the information the INE produces in electronic formats. The primary organisation of the information follows the theme-based classification of the Inventory of Statistical Operations of the State General Administration . The basic unit of INEbase is the statistical operation, defined as the set of activities that lead to obtaining statistical results on a determined sector or subject based on the individually collected data. Also included in the scope of this definition are synthesis preparation.

    
    

    Monthly and quarterly results for the period between the reference month corresponding to January 2013 and the last published month are available.

    There is information on the indices and monthly, quarterly, annual variation and year-to-date average rates at different levels of disaggregation according to the main activity of the statistical unit and about the weighting structure used in the calculation of the aggregated indices at this link.

    During 2022, the number of accesses to the INE website for consulting the tables containing information related to the Short-term Stock and Inventory Survey was:

    AC1=9.710 acceses

    And the number of accesses for consulting metadata has been:

    AC2=652 accesses

  • 10.4Micro-data access
    A lot of statistical operations disseminate public domain anonymized files, available free of charge for downloading in the INE website Microdata Section
    

    However, in the specific case of the Short-term Stock and Inventory Survey, anonymous microdata are not accessible to the general public and are not disseminated through any means.

  • 10.5Other

    It is possible to request tailored information through the INE Information Area.

    When processing these requests, limitations on confidentiality and accuracy must be borne in mind.

  • 10.6Documentation on methodology

    The methodological manual of this statistical operation can be consulted at the following link.

    The completeness of the metadata, AC3, is the percentage of metadata provided in relation to the total metadata required in the standardised methodological report.

    The completeness of the metadata of the Short-term Stock and Inventory Survey is AC3=100% because all sections of the methodological sheet were completed.

  • 10.7Quality documentation

    The Short-term Stock and Inventory Survey is prepared in compliance with the European Statistics Code of Practice that was adopted by the Statistical Programme Committee (predecessor of the European Statistical System Committee (ESSC)) in February 2005. The aforementioned Code, in which fifteen principles are established, has been adopted by INE as its own, in this way guaranteeing its fulfilment when establishing the general principles that regulate statistical production for state purposes.

    Throughout this report (fields 10.6 to 17.2), different quality indicators and different explanations for the validations and quality management carried out for this statistical operation are presented. Fields 10.6 to 17.2 of this document are the user-oriented quality report for this operation.

• 11Quality management
  • 11.1Quality assurance

    Quality assurance framework for the INE statistics is based on the ESSCoP, the European Statistics Code of Practice made by EUROSTAT. The ESSCoP is made up of 16 principles, gathered in three areas: Institutional Environment, Processes and Products. Each principle is associated with some indicators which make possible to measure it. In order to evaluate quality, EUROSTAT provides different tools: the indicators mentioned above, Self-assessment based on the DESAP model, peer review, user satisfaction surveys and other proceedings for evaluation.

    
    

    The development process of the Short-term Stock and Inventory Survey is designed to guarantee the quality of the information used, as well as that of the results obtained through said information. For this reason, in all stages of the process, various quality controls have been designed, such as the detection of invalid values, estimate of non-response and supervision and monitoring of fieldwork, as well as other permanent checks on the flow of information.

  • 11.2Quality assessment

    The Short-term Stock and Inventory Survey complies with the quality levels established by the INE.

    The sampling size allows for the collection of information on a national level, down to the division level of the NACE Rev.2.

    In terms of the survey limitations, the inherent limitations to statistical operations due to sampling, such as non-responses, must be noted. Furthermore, in the trade portion, the sampling errors or variation coefficients of the estimates must be borne in mind.

    Both limitations remain within reasonable limits.

• 12Relevance
  • 12.1User needs

    The survey responds to the information needs of its main users. These include:

    • Ministries and other public bodies
    • INE's National Accounts Department
    • Companies
    • Researchers and universities
    • Press and specialised media
    • Individuals

    Every one of these users has different needs regarding the destination and use of the information they require.

  • 12.2User satisfaction

    The INE has carried out general user satisfaction surveys in 2007, 2010, 2013,  2016 and 2019 and it plans to continue doing so every three years. The purpose of these surveys is to find out what users think about the quality of the information of the INE statistics and the extent to which their needs of information are covered. In addition, additional surveys are carried out in order to acknowledge better other fields such as dissemination of the information, quality of some publications...

    On the INE website, in its section Methods and Projects / Quality and Code of Practice / INE quality management / User surveys are available surveys conducted to date.(Click  next link)

     

    
    

    The persons responsible for the survey are permanently in contact with its main users, with the aim of attending to any specific information need.

    In addition, to deal with requests that may not be dealt with due to their complexity, whenever the base is changed these are assessed along with any suggestion made by the main users.

    Furthermore, on the INE website, in its quality section, there are different "User Satisfaction Surveys" where the Services sector (in which this statistical operation is located) is assessed, which can guide the opinion of users about it.

  • 12.3Completeness

    The survey responds to all the information requirements subject to national regulations.

    The indicator R1: rate of available obligatory statistical results, which is calculated as the quotient between the amount of data provided and the amount of data required by the applicable regulations, has the value R1=100%.

• 13Accuracy and reliability
  • 13.1Overall accuracy

    The different survey processes are aimed at eliminating or minimising errors of this kind, both in the collection phase (monitoring of the response rate and control of filtering of errors) as well as in the later phases of imputation of non-response and the calculation of aggregated indices, which allows a high level of reliability for the statistical operation to be obtained.

  • 13.2Sampling error

    The sample of the Short-term Stock and Inventory Survey formed by units whose main activity is classed as trade (section G in the NACE Rev.2) is probabilistic.

    More specifically, the sub-sample in which the inventory value of enterprises dedicated to trade is collected is based on samples of the Retail Trade Indices (RTI) and Services Sector Activity Indicators (SSAI), restricting them to the units whose main activity can be found within the target population and have a larger number of employed persons. For their part, the RTI and SSAI samples are also probabilistic and their sample designs are intended to minimise sampling errors in these.

  • 13.3Non-sampling error

    A non-sampling error check is carried out throughout the entire statistical process.

    In each of the surveys in which questionnaires included questions on inventories (RTI and SSAI), a continuous quantitative evaluation is carried out of non-sampling errors and the bias risks associated with:

    - Lack of coverage, excess coverage and duplicates in the framework

    - Collection instruments

    - Total non-response

    - Partial non-response

    - Editing, coding and imputation of data.

    Subsequent analysis of the results of this measurement with the aim of carrying out actions to reduce the different types of errors.

    Furthermore, an objective measurement based on the following quantitative indicators is carried out:

    A2: Over-coverage rate

    The over-coverage rate measures the proportion of eligible units , via the framework, that do not belong to the target population (they are outside of the scope).

    For 2023, the over-coverage rate is A2 = 7.6%

     

    A4: Non-response rate

    This non-response rate is calculated as the percentage of the number of units without information or with non-usable information with regards to the total units that can be sampled (that is to say, without counting framework errors).

    The average non-response rate, A4, for the results published on the inventory level in Trade in 2023 is:

    - For the first published version: A4 = 8.5%

    - For the latest published version: A4 = 4.0%

     

    A5: Non-response rate by item

    For the Trade inventory, this rate is calculated as the quotient between the units of the surveyed target population that did not respond to the question on the inventory level of merchandise at the end of the month and the units that were required to provide the aforementioned information.

    The average non-response rate for merchandise inventories, A5, for the results published on the inventory level in Trade in 2023 is A5= 1.8%

     

    A7: Imputation rate

    The imputation rate of Trade inventory measures the percentage of values assigned to the inventory level in the companies that lack these data, or where these data are invalid or inconsistent.

    The average imputation rate of merchandise inventories, A7, for the results published on inventory levels in Trade in 2023 is A7 = 5.1%

• 14Timeliness and punctuality
  • 14.1Timeliness

    In 2023, 65 days pass between the end of the calendar quarter and the publication of the results corresponding to this period. That is to say, TP1 = 65 days.

    Regarding the date of publication of the definitive results, the rates for each specific month will be provisional for five months. That is to say, TP2 = 5 months.

     

  • 14.2Punctuality

    The results of the Short-term Stock and Inventory Survey (ECSE) are published in accordance with what is provided for in the availability calendar of short-term statistics established by the INE in the last quarter of each year.

• 15Coherence and Comparability
  • 15.1Comparability - geographical

    The ECSE is not subject to any specific European regulation as its results are not directly comparable to those published by other countries due to the fact that the methodology and the variables studied in each of these are not the same.

    Although the survey has been designed homogeneously for the whole geographic territory, only indicators for the national total are published as it is not possible to release good quality results broken down by Autonomous Community.

  • 15.2Comparability - over time

    The ECSE was published for the first time in 2015, with base year 2010 and in October 2018 results were published with base year 2015 for the first time. This base change modified some methodological aspects of the survey, which has created breaks in the series that have been suitably treated to offer linked series from the initial publication period of the survey to now.

    The first reference month published with monthly indices on the inventory level is January 2013.

    Comparability through time is measured through the CC2 indicator, which is the number of comparable elements of a time series from its last break.

    The number of comparable data, CC2, is:

    - for the monthly data until the reference month corresponding to December 2023: CC2=132.

    - for the quarterly data until the fourth quarter of 2023: CC2=44.

  • 15.3Coherence - cross domain

    The questions on inventory are included, depending on the main activity of each statistical unit, in the RTI and SSAI questionnaires and, for this reason, comparisons and relations can be carried out between the inventory variables and other variables, such as the turnover value, collected in the aforementioned questionnaires.

  • 15.4Coherence - internal

    The estimates are completely coherent internally as they are based on the same set of data and they are calculated using the same estimation methods at all levels.

• 16Cost and burden
  • 16.1Cost and burden

    From the start, an attempt has been made to reduce the cost of this statistical operation as much as possible and, for this reason, instead of carrying out an ad hoc short-term survey to collect information relating to inventory value, the questions relating to these are included in a part of the sample of two existing surveys. Services Sector Activity Indicators and Retail Trade Indices.

    The estimated budget appropriation needed to finance the survey, as provided for in the 2024 Annual Programme, is 34.25 thousand Euros.

    Regarding the collection of data, completion via the internet is promoted as this is a flexible and secure method for respondents that, furthermore, allows for the provision of higher quality information. In any case, other methods are also available to the respondents (paper questionnaire via post, e-mail, fax, telephone, etc.).

• 17Data revision
  • 17.1Data revision - policy

    The INE of Spain has a policy which regulates the basic aspects of statistical data revision, seeking to ensure process transparency and product quality. This policy is laid out in the document approved by the INE board of directors on 13 March of 2015, which is available on the INE website, in the section "Methods and projects/Quality and Code of Practice/INE’s Quality management/INE’s Revision policy" (link).

    This general policy sets the criteria that the different type of revisions should follow:  routine revision- it is the case of statistics whose production process includes regular revisions-; more extensive revision- when methodological or basic reference source changes take place-; and exceptional revision- for instance, when an error appears in a published statistic-.

    
    

    The regular revision policy is that, in every publication, the indices from the last five months are revised, as these months are the only ones whose data could have changed when compared to the previous publication.

    In this way, only the indices from the last five months are provisional, with the other indices being definitive.

  • 17.2Data revision - practice

    To measure the average revisions to the published index, we use the indicators A6_MAR (mean absolute revision), A6_RMAR (relative mean absolute revision) and A6_MR (mean revision).

    
    For the annual rate of the total monthly trade index for the last 36 months (from January 2021 to December 2023):

    A6_MAR = 0.021

    A6_RMAR = 0.240%

    A6_MR = -0.001

    MaxAR=0.349 (Sept-21)

     

    For the annual rate of the total quarterly trade index for the last 12 quarters (from Q1 2021 to Q4 2023):

    A6_ MAR = 0.014

    A6_RMAR = 0.230%

    A6_MR = 0.000

    MaxAR=0.115 (2021Q3)

• 18Statistical processing
  • 18.1Source data

    Within the survey's framework is the Central Business Register (CBR), which is an organised register of information containing data on the identity, location, territorial distribution and classification by size and economic activity of companies and establishments.

    Questions relating to inventories have been included in the sample of the two existing surveys carried out for many years by INE: Services Sector Activity Indicators (SSAI) and Retail Trade Indices (RTI).

    More specifically, questions on inventories are included in questionnaires aimed at the following statistical units:

    - Of the sample of Services Sector Activity Indicators: companies from divisions 45 and 46 (except group 46.1) with 10 or more employed persons).

    - Of the sample of Retail Trade Indices: companies from division 47 with 10 or more employed persons including, furthermore, for groups 47.4, 47.5, 47.6, 47.7 (except class 47.79) companies that have between 3 and 9 employed persons.

    For this reason, the units that are included in the calculation of the inventory index are, approximately:

    • around 4,500 companies from the RTI sample
    • around 3,800 companies from the SSAI sample

    As mention before, the sample of this statistical operation comes from two short- term surveys prepared by INE:

    - Retail Trade Index (RTI)

    - Services Sector Activity Indicators (SSAI)

    Each of them has its own sample design, wich can be consulted in the corresponding methodology published on the INE website.

  • 18.2Frequency of data collection

    Data is collected monthly.

  • 18.3Data collection

    Depending on the main activity of the statistical unit answering the questionnaire, one of two available models of questionnaires is used. Thus in the case of companies that belong to the inventory sample and whose main activity is included in divisions 45 and 46 (except group 46.1), the same questionnaire is used as the one which collects the necessary information to prepare the Services Sector Activity Indicators; and in the case of companies from division 47, the same questionnaire is used as that which collects the necessary information to prepare the Retail Trade Indices.

    For this reason, the questionnaires of the two aforementioned surveys that are also intended for the Short-term Stock and Inventory Survey have been adapted to include various questions that enable the required inventory information to be collected. Thus, a section that collects information on the amount of merchandise inventories at the end of the month is included.

    The respondent companies send the data via the internet, via email, via telephone, via fax or via ordinary post (questionnaires completed on paper).

  • 18.4Data validation

    During the completion phase of the questionnaire, a system for detecting inconsistencies is used whereby the respondent completing the questionnaire via the internet is alerted to any possible inconsistencies and, therefore, is required to confirm or modify the information provided.

    When this information is recorded by INE's own staff, there is a control system that indicates possible inconsistencies that could arise. In this process, for data that contain discrepancies or anomalies, the staff responsible for the collection of information will contact the respondent to confirm or modify the information provided.

    Once the information is compiled, a data coverage control is carried out in order to guarantee the completeness of the recorded data, as well as to detect duplicates and coverage errors, non-responses, etc.

  • 18.5Data compilation

    Before starting the process that allows the indices that will be published on this statistical operation to be obtained, the non-response is analysed to impute a figure appropriate to those units that have not provided information corresponding to the reference month.

    Later, the data filtration process is implemented with information received by INE collection centres. The process consists of two phases: in the first, a microfiltration system is carried out, or the filtration of microdata, whilst the second consists of an analysis for eachlevel of aggregation, or macrofiltration.

    Microfiltration consists of verifying the validity of data from each unit, corresponding to the historic series provided by this. The analysis makes comparisons between months and years, so that data is validated without re-contact when its evolution is repeated periodically.

    The second part of the filtration is carried out once the data is processed together. Centralised filtration or macrofiltration can take place with aggregate information. In contrast with microfiltration, weightings for each activity are part of the calculation at this stage, variation rates for different levels of aggregation are taken into account etc. In the cases in which information from other sources is available, a coherence procedure is carried out between these and the survey results.

    With the aim of changing the base to the base of 2015, weightings were updated. Data was taken from the 2015 Structural Business Survey, in particular the inventory level at the end of 2015, and later these weightings have been updated to December of year t-1 to obtain the weightings that are used in the calculation of the indices of year t.

  • 18.6Adjustment

    Only information relating to the original series is released, which is why neither seasonal nor calendar adjustments are carried out.

     

• 19Comment
  • 19.1Comment