4.6. General guideline. As a general guideline, it is good practice to ensure that the enterprise and other surveys that are conducted for IMTS-related purposes possess the following characteristics: (a) survey design (survey frame, target variables, etc.) is in compliance with the recommendations of IMTS 2010; (b) surveys are organized and conducted as an integral part of the national survey programme in order to reduce the resource requirements by eliminating the possibility of duplication of work and by using applicable common concepts, classifications, questionnaire designs and sampling techniques, and to achieve maximum possible consistency with other areas of economic statistics and; (c) the reporting burden of the respondents is minimized in view of their increasing reluctance to complete many separate questionnaires. In this connection, it should be emphasized that the success and sustainability of the trade statistics surveys can be ensured only on the basis of effective institutional arrangements (see chap.V).
4.7. Business registers and survey frames. A business register is generally the main source of the sampling frame for enterprise surveys. The establishment of such a register is essential for the full coordination of source data that relate to the same business units. Countries with a high proportion of small and micro enterprises might complement the existing business register with listings of enterprises from other sources and with area frames based on agricultural, economic and population censuses. The central survey frame, consisting of a business register in combination with other enterprise listings and area frames, represents the backbone of the collection processes of source data that interface with businesses through direct profiling, surveys, feedback and use of administrative records. A good central frame should contain data about the businesses, including their names, addresses, economic activity, variables of size and potentially information about the life cycle of the firm. For operational reasons, a unique identifier could be assigned to each entity in the register and in the central survey frame. This unique identifier should be clearly mapped to the business number used by the administrative authorities so as to ensure that administrative data are correctly applied to the various entities in the register.
4.8. Consultation with respondents and selection of data-collection methods. Consultation with potential respondents is an essential requirement before the finalization of the questionnaire design and decision-making on the data-collection method. Since statistical questionnaires are frequently filled-out by accountants, the participation of another person or other person(s) of the enterprise with a good knowledge of the survey questions should be encouraged. The choice of the survey data collection method (mail, telephone, electronic, personal interview, etc.) depends on the country’s resources, preferences and characteristics of the respondents, and may vary for different sectors of the economy. It is good practice to give the respondents an opportunity to assess the questionnaire as well as the selected data-collection method in order to facilitate the amendments needed to increase survey efficiency and to ensure better harmonization with other economic surveys.
4.9. Standardization of surveys. Standardization of surveys and questions applied across different industries contributes to consistency of the collected information and facilitates an integrated statistical production process. Standardization should be comprehensive and encompass survey design, sample frame and questionnaire design. Survey design may need to compensate for a lack of willingness among data providers to complete many separate survey requests sent to them each year. A coordinated modular approach carried out through annual continuous data- collection instruments with intra-annual collection rounds, instead of separate specific-purpose surveys, offers the possibility of reducing response burden and cost while providing flexibility in case of changing information needs.
4.10. Survey forms. Special data-collection forms or electronic data requests should be designed and sent to the selected enterprises on a regular basis at pre-announced dates. Such surveys could request information similar to that normally contained in customs declarations. For simplification, enterprises may be requested to report cumulative trade from the beginning of the year, with the last month's trade separately identified, and to keep documents confirming their export-import transactions for a certain period of time, for verification purposes. Those documents may include copies of contracts, invoices, certificates of origin of goods, etc.
4.11. Simplified survey forms. It is advised that a simplified survey form be used for enterprises whose foreign trade turnover does not exceed an established minimum. Such a form may require that information be provided only on the statistical value of exports or imports for aggregated groups of commodities, by partner country.
4.12. Determining the adequate sample of enterprises for the survey. The strategy for determining the adequate sample of enterprises for a survey depends on the specific population of enterprises in the concerned economic sector. Some economic sectors are dominated by only a few large companies. In such cases, all those companies should be surveyed. This is generally the case for the trade in electricity, gas, and oil, as well as for courier services, and for national aircraft operators acquiring and landing goods abroad. Other economic sectors have many enterprises participating in international trade, and adequate sampling should then be applied. This could for instance hold for the shipping sector, which generally consists of a few large and many medium-sized and small companies in the population of enterprises. Ideally, the information on shipping companies is available from the business register and sampling can be conducted using a stratified approach based (for instance) on enterprise size and location. It is generally advised that all large companies and an adequate proportion of the small and middle-sized ones be included in the sample.
4.13. In the case of fisheries, for example, while exports and imports are dominated by big companies in many countries, this might not be the case in others. If there is a wide spectrum of small and medium-sized enterprises in a country, as well as significant activity in the informal sector (e.g. family owned), which together contribute noticeably to such trade, it might be necessary to survey them. Such surveys would require obtaining a sample frame using the information provided by economic and population censuses. This may also entail the need to supplement an enterprise survey with an adequate household survey (based on area frame sampling, since only coastal areas are of importance).