7.5. A population census, hereinafter referred to as a census, provides, at a specified time, reliable data on social, demographic and economic characteristics of all persons in a country or in well-delimited parts of a country, especially for small geographical units. The data include information on the size, composition and spatial distribution of the population as well as socioeconomic and demographic characteristics. It is a major source of social statistics, with the obvious advantage of providing reliable data, that is to say, data unaffected by sampling error. In general, the census collects information for each individual in a household, usually for the whole country or for well-defined parts of the country. Censuses are conducted periodically in a majority of countries in the world. The international recommendation is that a national census be taken at least every 10 years. Some countries carry out censuses more frequently because of the rapidity of major changes in their population and/or housing circumstances. For more information on population censuses, compilers are encouraged to refer to Principles and Recommendations for Population and Housing Censuses, rev.2.
7.6. The 2008 SNA defines a household as a group of persons who share the same living accommodation, who pool some, or all, of their income and wealth and who consume certain types of goods and services collectively, mainly housing and food. In other words, they are groups of persons with common economic interests.
7.7. The internationally endorsed recommendations for the organization of household sample surveys are contained in Designing Household Survey Samples: Practical Guidelines. The publication provides recommendations and good practices for such key issues as the planning and execution of surveys, sampling strategies, sampling frames and master samples, the documentation and evaluation of sample designs, the construction and use of sample weights, the estimation of sampling errors for survey data, non-sampling errors in household surveys, and data processing for household surveys. Many countries have in place household survey programmes that include both periodic and ad hoc surveys.
7.8. Compilers should familiarize themselves with the recommendations contained in Designing Household Survey Samples in order to be in a better position to participate in the planning and conducting of household surveys in their countries for the purposes identified in the present Guide. Household surveys are a widely used statistical tool. Many countries have, therefore, developed their own detailed methodological guidelines on their design and conduct.  Such guidelines are periodically reviewed and amended as necessary. It is good practice for compilers to participate actively in that process and develop amendments that would ensure that relevant needs identified in MSITS 2010 are taken into account.
7.9. Compilers are also advised to review International Transactions in Remittances: Guide for Compilers and Users, a publication of the International Monetary Fund (IMF), that suggests that household or labour force surveys be used to collect information relevant to mode 4 by including a number of specialized modules or questions in existing surveys, or that specialized surveys be conducted through which relevant households could be identified. Such practices would help analysts understand the relationships among such elements as the supply of services and employment status. Various means of specifically targeting the population of interest should be identified in order to avoid increases in the response burden the cost of using such sources and, as well as to ensure an adequate response.
7.10. As with any survey sample, the entities, both enterprises and individuals, surveyed must be representative of the population. Since there is no register for those travelling, compilers should look at administrative records or other sources that could serve as a register. For some countries, even measuring the number of people crossing the borders represents a challenge, for example, in countries with border unions, as is the case for European Union countries.
7.11. A survey of persons collects data pertaining to specific groups of individuals. Household surveys provide access to persons by first selecting households. Compilers can transform household surveys into a sample of persons through the following procedure: at the beginning of the interview, the interviewer asks how many persons above a certain age are permanent members of the household. From that range of persons, the target person (e.g., the oldest, the second-oldest, etc.) is chosen by a random procedure. The interview is then conducted with that randomly chosen target person only.
7.12. Owing to the unique nature of tourism (as described later in this chapter), such sample surveys of households and of persons as border surveys are often used to collect information for travel imports (debits) and tourism expenditures. Thus, given the importance of tourism and travel, some parts of the present chapter will frequently refer to the surveys conducted for tourism statistics purposes. Compilers should therefore have knowledge of the basic tourism statistics concepts in order to make appropriate use of such surveys in the context of MSITS 2010. Basic concepts of tourism statistics are provided in box 14.2 of the present Guide. For more detailed information, also see IRTS 2008 and its accompanying compilation recommendations.
Next: C. Population censuses
 Housing censuses may also be of interest. A housing census collects information pertaining to all living quarters and occupants thereof in a country or in a well-delimited part of a country.
 See 2008 SNA, para. 24.12. The 2008 SNA recognizes the importance of household surveys, but, at the same time, notes that the conventions adopted by survey statisticians and those of national accountants are not always the same. A household expenditure survey, for example, may not include estimates of the imputed rental of owner-occupied dwellings or own account production. It may measure income after tax, or expenditure on a cash basis, but not on an accrual basis. Compilers should be aware of such limitations when using those sources.
 Designing Household Survey Samples: Practical Guidelines, Studies in Methods, Series F, No. 98 (United Nations publication, Sales No. E.06.XVII.13). Available from http://unstats.un.org/unsd/publication/seriesf/Seriesf_98e.pdf.
 See also the International Household Survey Network at www.surveynetwork.org.
 Household surveys are extensively treated in Statistics Canada, Survey Methods and Practices, available from http://www5.statcan.gc.ca/bsolc/olc-cel/olc-cel?lang=eng&catno=12-587-X.
 See See International Recommendations for Tourism Statistics 2008 (IRTS 2008), Studies in Methods, Series M, No. 83/rev.1 (United Nations publication, Sales No. E.08.XVII.28), paras. 2.4- 2.12 and International Recommendations for Tourism Statistics 2008: Compilation Guide (IRTS 2008 Compilation Guide).