Classification and coding

The four basic criteria used to structure the 'Family composition' classification are applied in the following order: 

• Couple relationship.
• Parent-child relationship.
• Child dependency.
• Other blood relationship.

The first three of the above criteria are also used to determine 'Income unit composition'.

'Family composition' is a four level hierarchical classification from broad (level 1) through to detailed (level 4).

The code structure for 'Family composition' at all levels is presented below. The category titles are self-explanatory; brief descriptions may be found in the Glossary.

The categories in the classification are:

The category '9 Other family' is reserved as a residual category. All other level 1 categories in the classification are exhaustive and therefore do not require residual categories and codes.

Two types of supplementary codes are used to process inadequately described responses in statistical collections:

• those ending in zero are called 'not further defined' (n.f.d.) codes. These are used to code responses that cannot be coded to the four digit level, but can be coded to the three (with one zero), two (with two zeros) or one digit level (with three zeros)
• those commencing with zero are used to process the responses 'Not stated/Inadequately described', which do not provide sufficient information to be coded to any level of the structure, and when no response is given. In the Census the code '@@@@' is used for 'Not applicable'.

The 'Family composition' classification applies to all families. It also applies to households where a nominal parent has been designated for family coding purposes.

Responses to the 'Family composition' variable are coded directly to the codes of the classification, as described above.

There are nine rules for identifying a family and allocating individuals to it. These rules are listed below in the order in which they are applied.

Rule 1

A family can only be formed from persons usually resident in the same dwelling/household, one of whom must be 15 years of age or over.

Rule 2

A couple family exists if two people both 15 years of age or over have formed a couple relationship. This is defined as two people usually residing in the same household who share a social, economic and emotional bond usually associated with marriage and who consider their relationship to be a marriage or marriage-like union. The relationship is described by a respondent using terms such as 'husband', 'wife', 'spouse', 'de facto', 'partner' etc.

Rule 3

A lone parent-to-child relationship forms the nucleus of a family when the parent is not a partner in a couple relationship, the child is not a partner in a couple relationship, and the child has no children of his or her own living in the same household. If two or more children are present in a one parent family, the nucleus is formed between the parent and eldest child.

Rule 4

If two people in the household are related, but not through a couple family or one parent family relationship, they form the nucleus of an 'Other family'. Possible relationships that can form such families are listed in Rule 9 below. The nucleus of an Other family is formed by the two people with the closest relationship as described in Rule 7e below. An Other family can only be formed by people who are not related to any couple family or one parent family already present in the household.

Rule 5

People not directly forming the couple family nucleus or one parent family nucleus are allocated to the family nucleus to which they are most closely related. For example, children of a couple are allocated to that couple and children of a one parent family are allocated to the family nucleus of their parent and eldest sibling unless they form a couple or one parent family themselves.

Rule 6

A separate family nucleus is formed for each couple family and each lone parent family. If there is more than one family in a household, these are known as multi-family households.

Rule 7

The formation of the family nucleus and the subsequent attaching of people to this nucleus has a set of priority rules in both single and multi-family households. If there is any doubt about which way to form the family, use the following rules in the order listed below:

1. Most recent generation rule
2. Eldest child rule
3. Child to female parent rule
4. Closest relationship rule
5. Eldest relative rule

The first three rules apply predominantly to parent-child relationships. Rules 7d and 7e are used initially when doubt arises from family relationships other than parent-child relationships: only when these Rules are unsuccessful should Rules 7a, 7b and 7c be applied, in that order. Explanations of the Rules are provided below.

Rule 7a) Most recent generation rule

Where a lone parent-child relationship exists for more than one generation in the same household, the most recent generation forms the family nucleus. For example, if a household contains a 70-year-old parent with no partner present, a 50-year-old daughter and her 20-year-old son, then the 50-year-old and the 20-year-old form the family nucleus and the 70-year-old is attached to the family as a 'father/mother (other related individual)'.

An example of the most recent generation rule in a multi-family household is a household consisting of a couple aged 75 and 73 (= family 1) who live with their son aged 50, and his daughter aged 20 and her husband aged 22 (= family 2). In this case, the son aged 50 could be attached to family 1 as a 'non-dependent child' or family 2 as a 'father/mother (other related individual)'. The most recent generation rule attaches him to family 2, the younger family, as a 'father/mother (other related individual)'.

Rule 7b) Eldest child rule

Other situations where a person could be allocated to more than one family in the household may be resolved by the application of the eldest child rule. For example, take a multi-family household composed of a widower who lives with his son (aged 35) and daughter (aged 25), where the son has formed a family nucleus with a partner (= family 1) and the daughter has a child present, thereby forming a one parent family nucleus (= family 2). Using the eldest child rule the widower is attached to the family nucleus of his eldest child, i.e. family 1, as a 'father/mother (other related individual)'.

Rule 7c) Child to female parent rule

Where the parents of a child or children no longer consider themselves a couple but still live in the same household, then the child to female parent rule is used to form a lone parent family nucleus comprising the mother and eldest child, with other children of the mother attached to this nucleus. This rule is a generalisation that applies in the absence of data collection about custody arrangements. The father is attached to this family as a relative of the eldest child, unless he is part of a separate family nucleus.

Rule 7d) Closest relationship rule

In a multi-family household where a person is an 'other related individual' and is related to more than one family (e.g. they are an aunt to one family but a grandmother to another) he or she should be allocated to the family where the closer relationship lies. Relationships by lineage (vertical) take precedence over other types of relationships, for example grandmother over aunt, or aunt over cousin.

In a similar situation, where there is a multi-family household consisting of a couple aged 75 and 73 (= family 1) who live with their nephew aged 50, his niece aged 20 and the niece's husband aged 22 (= family 2), it is not possible to use Rule 7d to determine where the nephew's closer relationship lies. Therefore Rule 7a, the most recent generation rule, is applied and the nephew aged 50 is attached to family 2 as an uncle (i.e. as an 'other related individual').

Rule 7e) Eldest relative rule

In a multi-family household where it is possible to allocate a person to more than one family using the same relationship (e.g. she is an aunt to the family of either of her two nephews), the person is allocated to the family of his or her eldest relative.

Rule 8

Individuals can be attached to the 'other family' nucleus if they are related to either one of the people forming the nucleus or to any other person added to the 'other family' provided they do not form, or cannot be allocated to, a couple family or lone parent family in the household.

Rule 9

The following familial relationships are included in the definition of the term 'related':

In addition to this list, any direct ancestors (such as great-grandmother) or direct descendants (such as great-grandchild) are considered to be family members. However, any person more distantly related than cousin is not considered a family member. Adopted and foster relationships are treated as related; godparent and godchild relationships are not treated as related.

The ABS defines dependent children as comprising two groups: children aged under 15, and dependent students who must be full-time students aged between 15 and 24, and be a usual resident of the same dwelling as at least one of their parents.

Where a child under 15 is a usual resident of a dwelling where their parent is not a usual resident, the coding rules require the child be allocated a 'nominal parent', and in the process becomes a 'nominal child'. Any person who is allocated as a 'nominal parent' to a 'nominal child' is then coded as a parent and is indistinguishable from a birth, foster, step or adoptive parent. The concepts of the 'nominal parent' and 'nominal child' are used where, to all intents and purposes, a 'parent-child' relationship exists in a household. The aim is to allow coding of more consistent family and household structures.

Full-time students aged between 15 and 24 are never allocated nominal parents. Consequently if that student is a usual resident of a dwelling where their birth, step or adoptive parent is not a usual resident, the student cannot be defined as 'dependent' and becomes a related (or unrelated) person in that household.

A nominal parent is allocated to a nominal child by applying the following rules in the order shown below. The role of nominal parent is given to:

• The nominal child's eldest sibling who is over the age of 25.
• The nominal child's closest non-sibling relative aged 25 or more. If necessary, relationships by lineage (vertical) take precedence over other types of relationships, e.g. a grandmother over an aunt, or an aunt over a cousin.
• Persons in a couple relationship.
• A female in preference to a male, e.g. an aunt over an uncle.
• The eldest person usually resident in the dwelling.

The following examples illustrate the application of these rules. A child who usually lives with their uncle and aunt (who form a couple) and grandmother would be assigned to the grandmother (closest relative rule); a child usually resident with their aunt and an unrelated couple would be assigned to the aunt (closest relative rule); a child usually living with an unrelated couple and the sibling of the unrelated couple would be assigned to the couple (couple relationship rule); and a child usually resident with two or more relatives, e.g. an uncle and aunt who are siblings, would be assigned to the aunt (child to female parent rule). If the child resided with two uncles, he or she would be assigned to the eldest uncle (eldest person rule). Finally, a child usually resident in a dwelling with unrelated persons only would be assigned to the eldest female present or, failing that, to the eldest person.

Families are coded to the 'Family composition' classification by applying a simple series of consecutive criteria, which are, in order of precedence:

• Presence of couple relationship.
• Presence of children under 15.
• Presence of dependent students.
• Presence of non-dependent children.

The presence or absence of each of these criteria leads to the allocation of the appropriate 'Family composition' code. The decision-making process is represented in the following flowchart: