152. A census is not complete until the information collected is made available to users in a form and to a timetable that is suited to their needs and is fit for purpose. Furthermore, an important component of any country’s programme of dissemination is a comprehensive portfolio of supporting documentation and metadata to help explain, clarify and enhance the value of the statistical outputs, particularly with regards to making comparisons with previous censuses and other data sources.

153. The UNECE survey therefore investigated the form and other characteristics of the dissemination programme adopted by countries in the 2020 round. The results are presented in this chapter, which also briefly reports on how countries keep and maintain their census records in the long-term.

154. There are many ways of making the results of a census available to the users. In the past the census results were disseminated mainly by printed reports containing standard and pre-agreed tabulations. As long as the technology evolved, other dissemination methods emerged, including physical media (CD-ROM, DVDs), static web pages and, more recently, interactive online databases.

155. In the survey on practices in the 2020 round, countries were asked to indicate the primary dissemination method and any other dissemination methods used. Concerning the primary dissemination method, two were the most popular (Table 27). Static web pages were the primary method in 20 countries (43% of all reporting countries) and the favourite for field enumeration censuses (63%). Public interactive online tools were the primary method in 19 countries (40%) and the favourite method for combined and register-based censuses. In four countries the primary dissemination method was the EU Census hub and in three countries paper publications. In Austria no method was considered as primary.

156. Static web pages and public interactive online tools were also reported by many countries (23 and 18 respectively) as other dissemination methods. Other dissemination methods reported by many countries include GIS web-based mapping tools (27 countries), the EU Census hub (25 countries) and paper publications (18 countries).

157. The dissemination methods used by most countries, as primary or secondary method, are public interactive online tools (43 countries, 91%) and static web pages (37 countries, 79%). Paper publications were used for dissemination in 21 countries in total (in only 3 countries as the primary method), that is half the number of countries that used them in the 2010 round (42 countries, including 9 where they were the primary method).

	Primary dissemination method				Other dissemination method
	Total (47)	Field enumeration (16)	Combined (17)	Register-based (14)	Total (47)	Field enumeration (16)	Combined (17)	Register-based (14)
Static web pages	20	10	7	3	23	7	10	6
Public interactive online tools	19	3	10	6	18	6	8	4
EU Census hub	4	0	0	4	25	5	12	8
Paper publications	3	3	0	0	18	7	8	3
GIS web-based mapping tools	0	0	0	0	27	7	12	8
Interactive visual/output (games, videos, etc.)	0	0	0	0	9	4	5	0
No format is considered main	1	0	0	1	n.a.	n.a.	n.a.	n.a.

n.a. = not available

158. As noted above, an important component of any country’s programme of dissemination is a comprehensive portfolio of supporting documentation to help explain, clarify and enhance the value of the statistical outputs, particularly with regards to making comparisons with previous censuses and other data sources.

159. The UNECE survey accordingly asked countries to report on the range of documentation produced to support the dissemination of outputs. The results are shown in Table 28.

160. Among the options presented in the survey, the most common are methodological papers (38 countries out of 44 responding) and definitions (31), followed by release schedules/dates/plans (27) and publication of the census questionnaires (22).

161. It is notable that less than half of the respondents (19) produce a dictionary/glossary. This may underrepresent the actual availability, as terminology may be seen as part of definitions by some respondents.

162. A significant number of countries used visualization videos (10), half of them had a field enumeration census.

163. Concerning definitions and other metadata, see also the section ‎7.4.

	Total (out of 44 countries)	Type of census
		Field enumeration (14 countries)	Combined (16 countries)	Register-based (14 countries)
Methodological papers/reports	38	13	15	10
Definitions	31	9	13	9
Schedules/release dates/plans	27	8	12	7
Publication of the census questionnaire(s)	22	9	13	0
Data dictionary/Glossary of terms	19	6	8	5
User guides	18	8	8	2
Training videos	10	5	4	1
None of the above	4	1	1	2

164. In planning and preparing their censuses, almost all responding countries referred to international standards and guidelines (Table 29).

165. Of the 45 countries that responded, 41 (91%) referred to the CES Recommendations for the 2020 census round, 22 (49%) to the third revision of the United Nations’ Principles and Recommendations for Population and Housing Censuses, and 21 (47%) to other UNECE or Eurostat documentation, which for most of those countries was EU legislation or other documentation related to the 2021 EU censuses.

166. Other documentation reported by countries include the GSBPM, guidelines of the Washington Group on disability statistics and UNECE expert meetings.

	Total (out of 45 countries)	Type of census
		Field enumeration (14 countries)	Combined (17 countries)	Register-based (14 countries)
CES Recommendations for the 2020 Censuses of Population and Housing	41	13	16	12
UN Principles and Recommendations for Population and Housing Censuses	22	9	8	5
Other UNECE or Eurostat documentation	21	1	11	9
UN Handbook on Census Management for Population and Housing Censuses	15	5	8	2
Other UN documentation	3	3	0	0

167. Metadata plays a fundamental role in the census outputs, regardless of the census method adopted, as they enable users to assess the value of the statistical outputs and draw valid comparisons with data from previous censuses or other data sources.

168. In the section above on Documentation, information was provided on definitions and other metadata produced by countries to support the census outputs. In this section, more detailed information on types of metadata produced is presented (Table 30).

169. Almost all reporting countries (42 out of 45) stated that they provided metadata for definitions of terms and concepts. Other metadata products reported by many countries include data visualization (maps, charts etc.) (36 countries), methodological reports and papers (34), explanatory notes to the tables (29) and population bases/table populations (29).

	Total (out of 45 countries)	Type of census
		Field enumeration (15 countries)	Combined (17 countries)	Register-based (13 countries)
Definitions of terms and concepts used	42	12	17	13
Data visualization (maps, charts etc.)	36	13	13	10
Methodological reports and papers	34	9	15	10
Explanatory notes to the tables	29	10	12	7
Population bases/table populations	29	14	10	5
The census questions	27	10	16	1
Data quality measures: Overall	25	6	11	8
Data quality measures: Level(s) of imputation	24	6	10	8
Changes to definitions since previous census	21	6	9	6
Data quality measures: Level(s) of response	21	6	11	4
Data quality measures: For each topic	16	4	5	7
Data quality measures: Comparisons with other data sources	12	5	4	3
Commentary	12	5	4	3
Data quality measures: For each level of geography	7	2	3	2
Data quality measures: Confidence intervals	7	3	3	1
Coverage adjustments	7	3	3	1
Data quality measures: For each area	5	2	1	2

170. In preparing their metadata, 38 countries (84%) reported that both national and international metadata standards and guidelines were followed, 4 countries followed only national standards and guidelines, and 3 countries did not follow any standards or guidelines.

171. Only one third of the countries (15) reported that they consulted with users and potential users when preparing the metadata.

172. The UNECE survey enquired about the archiving policy and how long countries kept either the individual census records (or any images of them), or, in the case of register-based censuses, any linked data based on unit records. The responses are shown in Table 31.

173. The practices are quite different for the various census methods. For field enumeration censuses the majority of countries destroy the census returns (8 countries), after a period of time (6 countries) that is often between 1-5 years, or after the end of census processing (2 countries). Only 4 countries open to the public the returns/unit record files after a period of more than 50 years.

174. Similarly, for combined censuses almost all reporting countries (11) destroy the census returns, after a period of time (6), or after the end of census processing (5). Only one country opens to the public the returns/unit record files, after more than 75 years.

175. For register-based censuses, no countries reported destroying the data, and 4 countries make individual census returns publicly available for either socio-historical or genealogical research a long time after the census (100 years or more in 3 countries). This policy ensures that in the clear majority of cases the number of publicly accessible records that would refer to living individuals is minimised.

176. Of the 16 countries that reported other practices, 6 countries (including 4 with register-based census) keep microdata/electronic forms with no intention to open it and without prescribing any period for destroying it.

	Total (out of 45 countries)	Type of census
		Field enumeration (15 countries)	Combined (17 countries)	Register-based (13 countries)
Kept only for as long as they are required for data processing, then destroyed	7	2	5	0
Kept for a prescribed period of time, then they are destroyed	12	6	6	0
After 1-5 years	6	4	2	0
After 5-10 years	2	1	1	0
After 11-20 years	1	1	0	0
After more than 20 years	3	0	3	0
Kept for a prescribed period of time, then they are open to the public	10	5	1	4
After 30-50 years	1	0	0	1
After 51-75 years	2	2	0	0
After 76-100 years	3	2	1	0
After more than 100 years	4	1	0	3
Other	16	2	5	9