The annual Eurostat's collections on population are structured as follows:

Data Collection	Info& Legislation
UNIDEMO Unified Demographic	The most extended annual collection on demography and migration, collecting data at national and regional level for population, births, deaths, immigrants, emigrants, marriages and divorces by a large number of breakdowns. (Art. 3 of Regulation (EU) No 1260/2013 and Regulation (EU) No 862/2007)
URESPOP Usually Residence Population	Usually resident population for the purpose of the Qualified Majority Voting. See more specific metadata in here: URESESMS (Art. 4 of Regulation (EU) No 1260/2013)

Data referring to population on 31 December of the reference year are transmitted by the Member States to Eurostat under the Regulation 1260/2013 on European demographic statistics. The data are conventionally published by Eurostat as 1 January of the following year (reference year + 1).

Population on 1 January

Eurostat aims at collecting from the EU-27's Member States data on population on 1 January. The recommended definition is the 'usually resident population' and represents the number of inhabitants of a given area on 1January of the year in question (or, in some cases, on 31st December of the previous year). However, the population transmitted by the countries can also be either based on data from the most recent census adjusted by the components of population change produced since the last census, either based on population registers.

Usual residence means the place where a person normally spends the daily period of rest, regardless of temporary absences for purposes of recreation, holidays, visits to friends and relatives, business, medical treatment or religious pilgrimage. The following persons alone are considered to be usually residents of the geographical area in question:

• those who have lived in their place of usual residence for a continuous period of at least 12 months before the reference time; or
• those who arrived in their place of usual residence during the 12 months before the reference time with the intention of staying there for at least one year.

Citizenship denotes the particular legal bond between an individual and his/her State, acquired by birth or naturalization, whether by declaration, choice, marriage or other means according to national legislation.

Country of birth is the country of residence (in its current borders, if the information is available) of the mother at the time of the birth or, in default, the country (in its current borders, if the information is available) in which the birth took place.

Old age dependency ratio is the number of persons of an age when they are conventionally considered economically inactive (aged 65 years and over (1^st variant) or 60 years and older (2^nd variant) to the number of persons conventionally considered of working age (respectively aged 15-64 (1^st variant) or 20-59 years old (2^nd variant)).

The total age dependency ratio is the sum of the young and old age dependency ratios.

Median age of population

The age that divides a population into two numerically equal groups, meaning half the people are younger than median age and half are older.

Open-ended age class concept (Y_OPEN code) is a solution for presenting different open-ended age classes for data on population that are reported by the countries.

The open-ended age classes for data on population are the following: 85 and over (+), 90+, 95+, 99+, 100+ with the exceptions:

• Bulgaria: 80+ for the years 1994, 1995 and 1996
• Cyprus: 80+ for the years 1990, 1991 and 1992
• Turkey: 75+ for the years 2009, 2010 and 2011

Open-ended age class contains all the people aged more than the last single age for which a country can report. For example, if a country can provide data on its population by single year of age up to 94 years old, the ''open ended age class'' contains population 95 years old and over.

Statistical unit

Statistical unit used is ''person'' as indicated in the online database or deductible from the title of tables.

Coverage - Time

The available time series collected and published in Eurostat database varies with the population breakdowns, with the longest time series starting in 1960 for national data and 1990 for regional data, and continuing to the latest available reference year.

The completeness of the time series of the demography and migration statistics collected on voluntary basis before the entering into force of the regulations listed in "2.3. Institutional mandate" and of the statistics which continue to be supplied to Eurostat on voluntary basis today depends on the availability of data transmitted by the national statistical institutes.

Documents

Regulation (EC) No 862/2007 of the European Parliament and of the Council of 11 July 2007 on Community statistics on migration and international protection and repealing Council Regulation (EEC) No 311/76 on the compilation of statistics on foreign workers.

Commission Regulation (EU) No 351/2010 of implementing Regulation (EC) No 862/2007 on Community statistics on migration and international protection as regards the definitions of the categories of the groups of country of birth, groups of country of previous usual residence, groups of country of next usual residence and groups of citizenship.

Commission Regulation (EU) No 1260/2013 of the European Parliament and of the Council on European demographic statistics.

CommissionImplementing Regulation (EU) No 205/2014 of Regulation (EU) No 1260/2013

Commission Regulation (EU) No 31/2011 of 17 January 2011 amending annexes to Regulation (EC) No 1059/2003 of the European Parliament and of the Council on the establishment of a common classification of territorial units for statistics (NUTS) (legislation reflects NUTS-2010 classification currently available).

Commission Regulation (EU) No 1046/2012 on implementing Regulation (EC) No 1059/2003 of the European Parliament and of the Council on the establishment of a common classification of territorial units for statistics (NUTS), as regards the transmission of the time series for the new regional breakdown. (legislation refers to HTS NUTS-2010 classification currently available).

Commission Regulation (EU) No 868/2014 amending the annexes to Regulation (EC) No 1059/2003 of the European Parliament and of the Council on the establishment of a common classification of territorial units for statistics (NUTS). (legislation reflects NUTS-2013 classification currently in force; to be applied March 2016).

Commission Regulation (EU) No 1319/2013 of 9 December 2013 amending annexes to Regulation (EC) No 1059/2003 of the European Parliament and of the Council on the establishment of a common classification of territorial units for statistics (NUTS). (legislation reflects NUTS-2013 classification currently in force; to be applied March 2016)

Data collected on voluntary basis are:

• population by age and sex at national and regional level before the reference year 2013
• population by citizenship and country of birth before the reference year 2008
• annual data on various breakdowns of population which are not foreseen in the legislation above but are part of the Eurostat data collections

Summary of mandatory and voluntary population data collected by Eurostat:

Population by:	< 2008	2008-2013	>2014
age, sex, region	voluntary	voluntary	mandatory
5 year age group, sex, country group of CTZ/group of COB	voluntary	mandatory	mandatory
5 year age group, sex, single CTZ/ single COB	voluntary	voluntary	voluntary
age, sex, group of CTZ/group of COB	voluntary	mandatory	mandatory
5 year age group, sex, single CTZ/single COB	voluntary	voluntary	voluntary
group of CTZ, group of COB	voluntary	voluntary	voluntary
age, sex, legal marital status, education	voluntary	voluntary	voluntary

Where:

- group of CTZ= group of citizenship: nationals/non-nationals/unknown

- country group of CTZ= country group of citizenship: reporting, EFTA, candidate countries, stateless, etc.

- group of COB= group of country of birth: native born/foreign born/unknown

- ''mandatory'' refers only to the Member States and EFTA countries.

According to Art. 12 of the Regulation (EC) No 862/2007, "starting August 2012 and every three years thereafter, the Commission shall submit a report to the European Parliament and the Council on the statistics compiled pursuant to this Regulation and on their quality".

Therefore, information about overall assessment of data quality procedures carried out by Eurostat on the implementation of Regulation (EC) No 862/2007 on Community Statistics on Migration and International Protection is comprised in the Report from the Commission to the European Parliament and the Council, from 30.7.2015. This report documents the degree of progress that has been made by Member States, together with the Commission (Eurostat), in the implementation of the Regulation (EC) No 862/2007 since the first report.

In addition, Art 11 of Regulation (EU) No 1260/2013 states that Commission shall also submit reports on its implementation, to the European Parliament and the Council as follows:

- first report by 31 December 2018

- second report by 31 December 2023

These reports are to evaluate quality of data transmitted by Member States and EFTA countries and data collection methods used and, if appropriate, should be accompanied by proposals designed for future improvement of legal framework for population and vital events statistics under this Regulation.

The recommended definition of the population, in line with the Regulation 1260/2013, is the 'usually resident population' and means all the persons having their usual residence in a Member State at the reference time. Where the circumstances described above cannot be established, 'usual residence' can be taken to mean the place of legal or registered residence.

Definition of Population
Usual Residence	Legal Residence	Registered Residence
BG, CZ*, CY, DE, EE, EL, ES, FI, FR, HR, HU, IT, IE, IT, LV, LT, LU, MT NO, PL, PT, RO, SI, SK**, UK, * for non-nationals ** permanent residence	CH, LI	AT, BE, CZ, DK, DE, IS, ES, NL, SE

(table above is based on population 1 January 2014 reference year)

The population data for the year 2011 and after take into account the results of the latest population census (held in 2011). The time series of populations between the previous census and 2011 was revised by end 2013 by some of the countries, taking into account Eurostat’s recommendation.

Over time there have been geographical changes for certain countries:

• FR stands for Metropolitan France, including Corsica, excluding the overseas departments (DOM) before 1997. From 1998 on FR stands for the whole France, including the overseas departments (DOM).
• The time series for Germany (DE) refer to the Federal Republic within its frontiers after 3 October 1990.
• Starting from 1975, data for Cyprus (CY) refer to the government-controlled area.
• Up to 2000, population data for Malta (MT) refer to the Maltese population only while, starting from 2001, figures include also foreign resident. This is indicated by a flag b (break in series) in the figures for 2001.
• Since 2010, permanent resident population data of Switzerland (CH) includes all persons in the asylum process who have been residing in Switzerland since 12 months or more. The change appears in Eurostat population figures starting with population reported for 1.1.2011.
• Starting with 1.1.2011, Belgium (BE) population figures at national level refer to all registered persons including asylum seekers.
• Starting with 1.1.2012, the reported Estonian (EE) population includes the migration component, whereas this was not included before.

Controls are carried out on raw data transmitted by the NSIs to check if the total of a variable is consistent with the breakdown by different variables. Consistencies between different breakdowns of the same variable are verified by cross validations.

Based on the detailed collected data, Eurostat is computing a series of demographic statistics. The regular calculated demographic indicators are further submitted to several validations concerning the most updated annual value but also the available time series. These validations include checking on the plausibility of the most updated annual value and on two consecutive annual values. Mathematical verifications using standard deviation and weighted average are applied, for example for breakdowns of the life expectancy by educational attainment.

For more information on data validation see: http://ec.europa.eu/eurostat/data/data-validation .