Dissemination Workshop for African countries on the Implementation of International Recommendations for Distributive Trade Statistics 27-30 May 2008, Addis Ababa, Ethiopia UNITED NATIONS STATISTICS DIVISION Trade Statistics Branch Distributive Trade Statistics Section

Outline of the presentation National reporting Statistical confidentiality Data dissemination timetable Data revisions International reporting List of data items on DTS recommended for international reporting

National reporting Data dissemination Key activity of NSOs Responsibilities of NSOs Provide policy makers, business community and other users with high quality statistical information Motivate respondents to participate in statistical surveys Protect confidentiality of respondents

Statistical confidentiality Most of the information about individual statistical units classified in section G of ISIC, Rev.4 is considered to be confidential Statistical confidentiality is necessary in order to gain and keep the trust of: Those required to respond to statistical surveys Those using the statistical information UN Fundamental Principles of Official Statistics (the sixth principle) National Statistical Laws or other supplementary governmental regulations National definitions of confidentiality and rules for microdata access may differ, but they should be consistent with this fundamental principle

DTS and statistical confidentiality NSOs usually disseminate DTS in the form of various statistical tables The statistical confidentiality is protected if tabulated data do not allow statistical units to be identified either directly or indirectly, thereby disclosing individual information Direct identification - if data of only one statistical unit are reported in a cell Indirect identification - if individual data can be derived from disseminated data (e.g. because there are too few units in a cell, or because of the dominance of one or two units in a cell)

Statistical disclosure control Set of methods to reduce the risk of disclosing information on individual units Manifest themselves at the dissemination stage, however Pertinent to all stages of statistical production process Disclosure control methods - attempt to find an optimal balance between the improvement in confidentiality protection and the reduction in data quality Identification of sensitive cells - first step in statistical disclosure control Sensitive cells – cells that tend to reveal directly or indirectly information about individual statistical units

Methods for protecting confidentiality Aggregation A confidential cell in a table is aggregated with another cell and then the information is disseminated for the aggregate and not for the two individual cells Suppression Removing records from a database or a table that contains confidential data Primary suppression - values in sensitive cells are not published while the original values of the others are Secondary suppression - some other cells are also suppressed to guarantee the protection of the values under the primary suppression Other methods Control rounding – the original value of each cell is modified by rounding it up or down to a near multiple of a base number Perturbation – linear programming variant of the controlled rounding technique

Confidentiality rules for DTS Rules for protecting confidentiality of DTS - should be in line with the provisions of countries national legislation and practice Confidentiality criteria Number of units in a tabulation cell Dominance of a unit or units contribution over the total value of a tabulation cell Decision in respect to the exact definition of the confidentiality criteria in terms of number of units per cell and percentage of dominance - left to the NSOs Confidentiality rules may be relaxed in individual cases by requesting the permission of the dominating respondent (s) to disclose their data

Recommendations Countries are encouraged to develop their own statistical disclosure methods suiting best their specific circumstances If suppression is preferred as a method for protecting confidentiality of DTS Any data deemed confidential should be reported in full detail at the next higher level of classification that adequately protect confidentiality The confidentiality protection must result in a minimum loss of information

Data dissemination timetable (1) Advance release calendar Guarantees well established relations between NSOs as producers of DTS and the user community Countries should develop and announce in advance the precise dates at which DTS statistics will be released To be posted in the beginning of each year on the country’s statistical office website Timelines of DTS data Monthly – 45 days after the reference month Quarterly – 3 months after the end of the quarter Annual – 18 months after the end of the year

Data dissemination timetable (2) Issues of importance for the development of advance release calendar Timing of collection of initial data from major DTS surveys To what extent data derived from the major data sources are subject to revisions Timing of preparation of important national economic policy documents that need DTS as inputs Modes of data dissemination

Data revisions Essential part of countries practices on compilation of DTS Occur as a consequence from the trade-off between the timeliness of published data and their reliability, accuracy and comprehensiveness Conducted for the benefit of users - to provide them with data that are as timely and accurate as possible Affect both annual and short-term DTS but are more pronounced for the short-term data

Reasons for revision Revisions due to “normal” statistical procedures (current revisions) - conducted at regular intervals of time New information becomes available Change in the methodology Change in data source Change of base year Revisions due to the correction of errors that may occur in source data or in processing Special revisions - carried out at longer, irregular intervals of time Re-assessing the data Investigating in depth some new economic structures

Revision policy Countries are encouraged to develop a well-designed, carefully managed and coordinated with other areas of statistics revision policy for DTS Essential features of a well-established revision policy Predetermine schedule Reasonable stability from year to year Openness Advance notice of reasons and effects Easy access of users to sufficiently long time series of revised data Adequate documentation of revisions included in the statistical publications and databases

Dissemination of metadata Provision of an adequate metadata and quality assessment of DTS is as important to users as provision of data Countries are encouraged to develop and disseminate metadata on DTS Metadata components Data coverage, periodicity and timeliness Access by the public Integrity of disseminated data Data quality Summary methodology Dissemination formats

International reporting – Annual data

International reporting – Quarterly data

International reporting – Monthly data

Thank You