B. General purpose and description of enterprise or establishment surveys
6.6. Business surveys can be conducted at the establishment or enterprise level and can provide coverage across the full range of services. They have proven successful for the collection of trade in services data and FATS in many countries. Detailed descriptions of the types of surveys and their design, as well as sampling techniques and related data editing and compilation procedures, are described in a number of publications, most notably in chapters 2 and 3 of the BPM6 Compilation Guide, which compilers are advised to consult when developing enterprise or establishment surveys for trade in services and balance of payment purposes. Compilers also are advised to make sure that the national definitions of the statistical unit (see chapter 5) comply with the standard definitions, and document any deviations in metadata.
6.7. One of the first decisions to be made in collecting data is whether to undertake a census, or to compile data from a sample survey that balances data quality with other considerations, such as reporting burden (see chapter 11 for a comparison of data sources). In determining the reporting population, various approaches are possible, including a census, a partial coverage collection survey, a random sample survey and a stratified random sample survey. In practice, compilers in many countries use a combination of two or three approaches when collecting data from enterprises, benefiting from their respective different advantages.
6.8. Surveys should always be based on clearly defined objectives, sound collection methodology and a well-established legal basis. Properly designed collection forms, full coverage of the population and well-defined data structures and classifications, as well as effective data validation and aggregation procedures, are also required. The principal steps of good survey design include the following:
(a) Specification of the objectives and coverage;
(b) Establishment of the sampling unit and the information to be collected;
(c) Determination of the appropriate sample size, if a sample will be used;
(d) Development of a sampling frame, i.e. an exhaustive list from which sampled units are selected;
(e) Development of the sample design, i.e. how the sample is selected from the frame;
(f) Determination of the method of collection (paper or electronic form, interview, etc.).
6.9. Sampling techniques and contacts with respondents Compilers can choose from a wide variety of sampling techniques; generally, these are either probabilistic or non-probabilistic. In probability sampling, every unit in a population has a calculable probability of being selected in the sample. That approach is objective and defensible. There is a theoretical basis for the process of extending the sample results back to the population. In probability sampling, estimates of sampling error can be calculated, and inferential statistics can be derived. Non-probability sampling methods should be used with caution, because there is no way to measure their precision. The only way to address the quality of the survey data produced in non-probability sampling is to compare the results of the survey to some known information about the population. A frequently used non-probability sampling method is cut-off sampling (see box 6.1).
6.10. Whether selecting a sample using probability or non-probability techniques, compilers must define the universe (population) from which they will sample, that is, in practical terms, construct a sampling frame. In most countries, it is possible to define the population using various lists of enterprises (business registers), compiled for administrative purposes. For more information on sampling techniques, sample frame, sample structure and sample allocation (how to allocate the data collection among the strata), it is suggested that compilers consult chapter 5 of the IMF Producer Price Index Manual. While the Manual focuses on price collection, much of the information can be applied more generally to enterprise or establishment surveys.
6.11. Collaboration with respondents to surveys is essential for the production of good-quality statistics, as explained in more detail in chapter 2 of the BPM6 Compilation Guide. It is recommended that compilers hold consultation meetings to make respondents aware of the purpose of the survey and to help the statistical agency design the survey.
 For example, see Ad Willeboordse, ed., Handbook on the Design and Implementation of Business Surveys, available from http://epp.eurostat.ec.europa.eu/cache/ITY_OFFPUB/CA-09-97-818/EN/CA-09-97-818-EN.PDF; and Eurostat, Survey Sampling Reference Guidelines: Introduction to Sample Design and Estimation Techniques, Eurostat Methodologies and Working Papers (Luxembourg, Office for Official Publications of the European Communities, 2008, available from http://ec.europa.eu/eurostat/ramon/statmanuals/files/KS-RA-08-003-EN.pdf. Many countries have published their guidelines, as well.
 See BPM6 Compilation Guide.
 Ibid., pp.13-14, for a more detailed explanation about survey forms and their advantages and disadvantages.
 Ibid., para. 2.3.
 IMF, Producer Price Index Manual: Theory and Practice (Washington, D.C., 2004). Available from https://www.imf.org/external/pubs/ft/ppi/2010/manual/ppi.pdf.
 Likewise, the Eurostat Survey Sampling Reference Guidelines provide more detailed information on that topic.
 See BPM6 Compilation Guide, para. 2.29.