Age refers to a person's age in whole years as at 31 December. The data are obtained from the Population Information System.
Age is also used as an auxiliary variable. For example, only people between 15 and 74 can be in the labour force.
In the family statistics children comprise the following persons living with their parents:
Foster children and children in the care of the family are not classified as children.
The definition of child has changed since 1990. A child is now defined as a person who lives with his or her parents irrespective of his or her marital status, unless the person has a spouse or children who live in the same household-dwelling unit. In 1990 only unmarried persons were counted as children. So while in 1990 widowed or divorced persons living with their parents were classified as not belonging to families, since 1992 they have been regarded as members of the family.
A cohabiting couple is defined as two spouseless adults of different sex aged 18 and over and occupying the same dwelling on a permanent basis, provided their age difference is less than 16 years and they are not siblings. In case the couple has a common child these specifications do not apply. Same-sex persons living together are not inferred as cohabiting couples. Only registered partnerships are recorded in the statistics.
A family consists of a married or cohabiting couple or persons in a registered partnership and their children living together; or either of the parents and his or her children living together; or a married or cohabiting couple and persons in a registered partnership without children.
Starting from 1 March 2002, same-sex couples have been able to register their partnerships.
Persons living in the household-dwelling unit who are not members of the nuclear family are not included in the family population, even if they are related, unless they form their own family. Brothers and sisters or cousins living together are not a family and do not belong to the family population. The same applies to people who live alone or with a person of the same sex.
Families living in residential homes are included in the family population. In contrast, persons who live in institutions are not included.
A family can consist of no more than two successive generations. If the household-dwelling unit comprises more than two generations, the family is formed starting from the youngest generation. This means, for example, that a mother-in-law or father-in-law living with their child's family will not be included in the family population unless they live together with their spouse, in which case the old couple form their own family.
A family with underage children refers to a family which has at least one child aged under 18 living at home.
Family members are grouped by family status as follows:
In the family statistics children comprise all persons, regardless of age, who live with their parents, or the spouse's biological or adopted children, but not foster children or children in the care of the family.
A family with underage children is a family comprising at least one child aged under 18 living at home.
Information on language is obtained from the Population Information System. At the same time as parents register the name of their new-born, they also indicate the child's mother tongue. That language is retained in the Population Information System unless it is changed upon separate application.
Languages are classified by the Population Register Centre according to the ISO 639 standard. The future language classification ISO-639-1 was already adopted for the 2000 population census.
The number of children refers to the number of children who are living at home and have the status of a child. The number of children in families with underage children refers to the number of children aged under 18 living at home.
In a reconstituted family, a child aged under 18 is a child of only one of the spouses. Not all the children aged under 18 in the family are common children.
Families are grouped into the following types:
A married or cohabiting couple without children refers to a couple who has never had any children or whose children no longer live with their parents. 'Cohabiting couple with children' contains couples who have common children and also couples whose children are not common.
For reasons of data protection, those living in registered partnerships are grouped together with married persons in municipal tables.
A man with a family is a married or cohabiting partner, a father with children and both partners of a registered male couple.
A woman with a family is a married or cohabiting partner, a mother with children and both partners of a registered female couple.