Most of the countries (31 out of 44) estimate population on the basis of census. This method was used either in isolation (by 18 countries) or in combination with a register (DE, ES, FR, LV, LT and HU)¹, (IE, HR, ME, RS and XK) or both (MT and RO. Except where legislation relevant to the population count enters into force on 1 January. This is the case with changes to geographical area; e.g. on 1 January 2014, Mayotte became part of the economic territory of France and there was a significant difference between the French population on 31 December 2013 and that on 1 January 2014. Population registers are the second most commonly used source for estimating population: they are used by 20 countries (BE, DE, DK, ES, FR, IT, LV, LT,HU, MT, NL, AT, RO, SI, FI, SE, LI, NO, CH and TR), of which six combine them with census information, one (IT) with information from surveys and two with both census and survey.
The most common reference date for counting population is 1 January, followed by 31 December. The difference between these two dates is actually nil² at national level: the population is usually the same on1 January of calendar year t as on 31 December of calendar year t-1. IE and UK use mid-April and 30 June respectively as reference dates. Also BA uses the mid-year reference date. CZ, ME and RS use all three reference dates (1 January,31 December and mid-year).
In order to measure the population, one has to define it. Four main definitions are used,³ each based on different principles determining whether or not a given individual is included. In general, the principles used reflect national data needs; they are as follows:

1. de jure population - this is based on a persons legal right to settle in the country; it therefore covers all persons who, on a given date, either have citizenship orhave been granted a residence permitor visa;
2. de facto population - all people present in the country at the time of the counting regardless of whetherthey have residence;
3. registered population - all persons listed in one or more registers kept by the national authorities on the reference date; and
4. usually residentpopulation - persons who⁴:

lived in the country for a continuous period of atleast 12 months before the reference time⁵; or

arrived in the country during the 12 months before the reference time with the intention of stayingthere for at least one year

The definition recommended by the Conference of EuropeanStatisticians (CES)⁶ and incorporated in the EUs population and housing census Regulationis⁷ based on place of usual residence. Usually resident population is the most widespread definition: 34 of the 44 countries surveyed reported using it, of which 23 use it in isolation, four (FR, RO⁸, FI and CH) use it in combination with the concept of legal population, four (DE, ES, IT, XK) refer to it together with registered population and three (BE, PL⁹ and NO) use three concepts. The second most commonly used definition is registered population: this was used in isolation by seven countries (CZ, DK, NL, AT,SE, MD and RO), in combination with legal populationby two (SK and TR) and together with de facto population by one (MD). The only country that uses legal populationonly is RS.

As regards the definition of usual residence, most countries (33 out of 44) apply a time criterion of 12 months or at least 12 months. Nine countries report having no time criteria. Of the 33 countries referring to the usually resident population and applying a 12-month or an at least 12 months criterion, 11 (IRL, HRV, CYP, HUN, PRT, UKR, MLT, LIE, MNE, SRB and ALB) mention intention to stay in the country for (atleast) this amount of time as a key criterion.

Most countries use the standard international definition of 'live birth'. As defined by the World Health Organisation (WHO), a live birth is the complete expulsion or extraction from the mother, irrespective of the duration of the pregnancy, of a baby which then breathes or shows any other sign of life, such as beating of the heart, pulsation of the umbilical cord or definite movement of the voluntary muscles, whether or not the umbilical cord has been cut or the placenta is attached. Each product of such a birth is considered 'live born'¹⁰.

Deaths are registered in all 44 countries surveyed, i.e. all people who die in the countries' 'territories are, in principle, registered as deceased.
In almost all countries, doctors or relatives can fill in the declaration of death, which must be made at a local or district civil registration office. In several countries the information in this document is complemented by other sources, such as a separate declaration made by a doctor or a statistical questionnaire collected simultaneously with the registration of death²⁰.
Time limits for declaring a death are generally much shorter than those for declaring a birth. In the majority of the countries surveyed, deaths must be declared within zero to seven days. However:

in AL, AZ and TR, deaths must be declared within 10 days;

in IE and CY, the declaration can be made as much as a year later; and

there is no time limit in NL

Infomation about death declarations vary between the 44 countries. The date of death is included in declarations in all countries and the name and date of birth of the deceased in all except BE, NL (name excluded), FI, SE and NO (name and date of birth excluded).
16 countries do not register the age of the deceased, although in all these countries except FI, SE and NO this information could be derived from processing.
32 countries (FI, SE and NO included) register the personal identification number (PIN), whereby in a number of countries the declaration can be linked to other registered data.
The deceased's religion is registered in CY, DE (till 2013) and RS, while the highest level of educational attainment is registered in BE, BG, CZ²¹, EE, EL, HR, IT, HU, PL, PT, RO, SK, ME, TR, BY, BA, XK, MD, RU, AM and AZ. EE also records place of burial.
Citizenship and country of birth are registered by 32 and 30 countries, respectively, while marital status and cause of death are recorded by 37.
EE, EL, IT, CY, HU, RO, SK and BA register the most items on the death declaration, while FI and SE register only a very limited amount of information. However, several countries can link different sources in order to obtain more information. In NL for example the declaration of death is made up by the general practitioner (doctor) and sent to Statistics Netherlands through the municipal authority where the person has died. The information in the document is combined with the population registry information available at Statistics Netherlands. Secondary variables like: country of birth, date of birth, address, sex etc. are obtained from the register, not from the death declaration itself.

Deaths are registered in all 44 countries surveyed, i.e. all people who die in the countries' 'territories are, in principle, registered as deceased.
In almost all countries, doctors or relatives can fill in the declaration of death, which must be made at a local or district civil registration office. In several countries the information in this document is complemented by other sources, such as a separate declaration made by a doctor or a statistical questionnaire collected simultaneously with the registration of death²².
Time limits for declaring a death are generally much shorter than those for declaring a birth. In the majority of the countries surveyed, deaths must be declared within zero to seven days. However:

in AL, AZ and TR, deaths must be declared within 10 days;

in IE and CY, the declaration can be made as much as a year later; and

there is no time limit in NL

The minimum legal age at which men and women can marry without parental consent is 18 in all the countries except AT, where it is 16. In most countries, younger people can get married if a courtor parents/guardians grant permission, or if certain specified conditions are met.
In 20 countries, 16-year-olds can get married with parental consent. In EE, LT, SI, AL, BY and XK the minimum age is 15 and in ES it is 14. In EL, men may be allowed to marry when they are 14, while for women the minimum age to receive court permission to marry is 12. In four countries (EL, LU, AT and PL) the legally required age to marry is not the same for men and women, with a difference of two years.

Marriage declarations exist in all countries except DK. In most countries, the date and place of marriage, the names of the spouses, their surnames before marriage, their dates of birth, nationality and previous marital status are recorded on the marriage certificate.
Other information included in the certificate varies widely among countries. For example, information on the spouses' highest level of educational attainment is included in 17 countries (CZ²⁴, EE, EL, HR, IT, HU, PL, PT, RO, SK, ME, TR, BY, BA, XK, AM and AZ). Nine (DE, EL, HR, CY, LV, AT, CH, BA and XK) collect information on their religion. 12 countries (DE, EE, LU, HU, AT, PT, NO, CH, BY, XK, RU and AZ) register how many children each of them has (either together or from previous relationships)²⁵.
In HU for example, surnames before and after marriage are included in the marriage declaration, but not recorded in the statistical database. Home address is available at settlement level and information on both spouses' country of birth will be available from 2014.
Information on both spouses' economic activity status is collected in HR, EL, HU, IT, PT and RO.
In the EU, the countries that collect the most information on the marriage declaration are EE, EL, LV and PT (13 items of the 15 selected); outside the EU, XK collects 14 items out of 15.
However, countries can link different sources in order to obtain more information. In NL the data on the marriage declaration document is integrated in the population registry system. This in turn allows for access to secondary variables like date of birth of the spouses, their address, citizenship etc. In PT, the collection of data on marriages for statistical purposes includes information from the civil registry (marriage registration) as well as a set of other variables collected simultaneously in an electronic questionnaire.

Unlike births and deaths, which involve individuals, marriages are contracted between two persons, who do not necessarily belong to the same population. Also, they may be contracted outside the country of residence of one or both of the spouses. It is therefore useful to distinguish between the following situations:
Case 1 represents the most common situation: two people who reside in the same country and get married in that country. In this case, the marriage certificate is drawn up in that country, the marriage is entered in the marriage statistics of that country and no other country is involved, either administratively or in terms of population statistics.

Looking at the other cases from the point of view of spouse 1 or his/her country of residence respectively:

in Case 2, the spouses reside in different countries but the marriage is contracted in the country of spouse 1;

in Case 3, the spouses have residence in the same country, but get married elsewhere; this is common among immigrants; and

in Case 4, the spouses come from different countries and decide to get married in a third country.

Case 2 marriages are generally treated and counted no differently from other marriages. Marriages contracted abroad (i.e. Cases 3 and 4) are registered in 30 of the 44 countries surveyed. Of these, 11 (BE, HR, CY, FI, LI, MD, NL, RS, SK, SI and TR) register all marriages of their residents that take place abroad, others apply various criteria to determine whether or not a marriage is registered:

ES, RO and NO register only those marriages where at least one spouse has citizenship of their country;

LT registers only those marriages where at least one spouse is usually resident in LT;

SE registers only those marriages where both spouses have SE citizenship;

DE, EE, XK and GE register their citizens' marriages only if the spouses officially request it.

Of the countries that register marriages taking place abroad, 20 include them in their national statistics, while BE, BG, EE, CY, PL, SI, ME, RS, TR and RU do not. In the remaining countries, there is no legal requirement to register such marriages.

Marriages of 'non-residents' are registered in 26 countries, but 14 (BG, CZ, EE, HR, LV, LT, NL, AT, PL, SI, SE, CH, RS and BA) do not include these in national statistics.

Most countries' national statistics include marriages of residents contracted abroad and exclude marriages by 'nonresidents'. However:

CZ includes only cases where at least one spouse has a registered residence in the country, regardless where the marriage is contracted;

BG, EE, AT, PL, SI and RS exclude both categories;

IE, EL, FR, IT, CY, HU, PT, UK and ME normally base their marriage statistics on marriages contracted in the country, irrespective of the spouses' countries of residence; they exclude their residents' marriages abroad; and

DE, MT, ES, RO and XK include both categories; their marriage statistics include all marriages contracted in their countries (irrespective of the spouses' countries of residence) and all their residents' marriages abroad.

Since the 1960s, living arrangements other than marriage have become more common in Europe. Some countries have fully or partially legalised living arrangements other than marriage, and allow couples with such arrangements to be registered in a more or less similar way to married couples. These arrangements became common practice in the north of Europe much earlier than in the south.
Among the 44 countries surveyed, legal/civil unions are allowed in 19 (BE, CZ, DK, DE, ES, FR, IE, EL, LU, HU, MT, NL, AT, SI, FI, SE, UK, NO and CH). In CZ, DE, HU, AT, FI, SI, UK and CH, registered/civil partnership status is reserved for same-sex couples and in EL for heterosexual couples. In the rest of the countries where legal/civil unions exist they are possible both for heterosexual and same-sex couples.
Legal/civil unions are usually registered by municipalities. In DE and MT, this is done by the registrar’s office, in SI by the ministry of interior and in NO by the tax administration.
In CZ, only registered same-sex partnerships are codified, but the data are not collected for statistical purposes. BE produces statistics on legal cohabitation but not on legal unions.

In most countries divorces are decided upon by the court and almost everywhere a divorce has to be requested by one or both partners. Additional remarks can be made for a number of countries, as follows:

in nine countries (BE, CZ, DE, EL, LV, LU, NL, XK and RU), 'structural disruption of the marriage and no prospect of reconciliation' is one of the conditions for obtaining the divorce;

in FR, LT, MT, UK and XK, adultery is one of the possible reasons for granting a divorce; in CZ, LT and RU, the marriage has to have lasted for a certain amount of time;

in six countries (CZ, DE, LV, FI, XK and RU), the couple has to have lived apart for a certain amount of time (usually one year); in CH, two years of separation are required to obtain the divorce (unless serious reasons rule out continuation of the marriage); in CY and IT three years of legal separation is the main condition for obtaining a divorce;

five countries (CZ, NL, SI, XK and RU) require proper provision for dependents (children, elderly people) before a divorce is granted;

in LV, a divorce can be obtained for reasons linked to a threat to a partner's life or health, but also when one of the spouses is cohabiting with another person with whom they have had, or are expecting, a child;

in PT, the divorce might be requested by one spouse against the other (divorce without the consent of a spouse, requested in the court) or of both (divorce by mutual consent, requested in the civil register). Grounds for divorce without the consent of a spouse are: a de facto separation for a year, the change of the mental faculties of the other spouse when this has lasted for more than a year and its severity compromises the possibility of life in common; the absence without any news of the absent for at least a year, and any other fact which shows the rupture of marriage, regardless of a fault of the spouses;

in SK, the conditions for granting a divorce include factors relating to the personal behaviour of the spouses.

In general, the declaration of divorce is a legal document to be filled in by the relevant court after it has pronounced its judgment. Such documents are issued in 36 of the 44 countries surveyed. In MT for example no certificate is issued, instead there is an annotation on the side of the marriage/civil union certificate.
The contents of these certificates vary widely across countries. EE and HU include the most information on such a certificate, followed by TR, GE and ME. Date of registration of divorce, date of marriage, date of birth and citizenship of both ex-spouses are the most commonly registered data. The number of common children is also included in 17 and the highest level of educational attainment in 15 countries. In EE, IT, RS and AM, certificates indicate the ex-spouses' socio-economic status. In BG, CZ, DE, IT, CY, LU, HU, PL, PT, RO, SK, CH and TR, the certificates also include information on the reasons for the divorce/dissolution.
Like in the case of the other declarations, the declaration of divorce is a general indication of the information available for statistical offices, but not necessarily the only source of information. In PT there are two instruments/declarations that support data collection: one for divorces granted in Court and another for divorces granted by the Civil Registry. For NL the gathering of the information follows this process: the information in the divorce declaration is sent to the municipality where the former spouses live and is integrated there in the population registry system. Secondary variables like date of birth of spouse, address, citizenship etc. are drawn from the register not from the marriage dissolution certificate. A number of variables like marriage order for example, are deducted from registry information within Statistics Netherlands. Similarly, in BG information on date of birth of both partners, their place of birth, home address, age country of birth, citizenship can be derived from the register. In UK age at divorce is derived while processing from age at marriage.

Of the 29 countries that register divorces abroad, 18 (CZ, DK, FR, IT, LT, MT, NL, PL, RO, FI, SE, LI, CH, BY, XK, MD, RU, GE) include these data in their national statistics. Divorces involving 'non-residents' are registered in 26 countries, but of these they are included in national statistics in 12 (EL, ES, FR, IT, HU, MT, PT, RO, UK, NO, XK and AZ). Five countries (FR, IT, MT, RO and XK) include both in their national statistics.
Duration completed at the time of divorce is used for the definition of duration of marriage at time of divorce in all the countries surveyed except DK, FR, LV and AM, which exclusively use duration reached at the end of the calendar year in their statistics. 11 countries (CZ, EE, IE, LU, NL, SK, SE, NO, CH, BA and GE) use both definitions.