Underlying concepts

The name of the variable is 'Relationship of non-primary family to primary family'. The standard abbreviated name is 'Relationship between families'.

The Census of Population and Housing provides output about such relationships and currently identifies up to three families in a household. In the 2011 Census the 'Relationship Between Families (RFLF)' variable was a family level variable that classified the relationship between the primary family and the second or third family enumerated in the same household. To identify the second and third families, the variable Family Number (FNOF) was required.

The relationship between families within a household is the relationship (familial or non-familial) of the second and any subsequent families to the primary family.

The relationship between families is measured by determining the relationship between the family reference person in a non-primary family to the family reference person in the primary family. The family reference person is determined by taking one person and then describing each other person's relationship to that person (see 'Discussion of conceptual issues' below). This allows the relationship between other members of the household to be identified and described.

The relationship is established by:

1. Identifying the families which exist in a household.
2. Identifying the family reference person in each family.
3. Identifying the family relationships of the second, third or subsequent family reference persons to the primary family reference person.
4. The relationship established by (c) then becomes the relationship of family 2, 3 or subsequent families to the primary family.

Relationship between families is an attribute of the counting unit 'family'.

NOTE: The number of families in a household is identified through the operationalisation of 'Family number', (see Glossary) which is a single-digit code assigned to each person to indicate to which family that person belongs.

The coding of a household member's relationship is based on the household relationship data collected in the 'Relationship in household' questions (see 'Relationship in household - Collection Methods'). The data, as originally collected, are dependent upon whom the respondent nominates as the household reference person. To achieve good quality data about family relationships, a standard is applied to ensure the accurate identification of the household or family reference person. If a respondent has nominated the wrong person, the correct person can be chosen by applying the standard hierarchical criteria as follows: 

• one of the partners in a registered or de facto marriage, or
• a lone parent, or
• the person with the highest income, or
• the owner, purchaser or primary rent payer of the household accommodation, or
• the eldest person.

Allocation of relationship codes in multi-family households is complex. Relationships in a household must be allocated on a family basis for each member of a family within the household. To facilitate this process, each family is separately identified by assigning a unique family number to each of its members. The 'Relationship in household' classification is then applied separately to each family in the household in turn (see the 'Relationship in household' standard and the Glossary).

Because the selection of household and family reference persons determine the relationships described, the types of relationships between families can be somewhat arbitrary depending on whom is selected. For example, in a household consisting of two cousins, their husbands and children, the category could either be 'Other related family' or 'Unrelated family' depending on whether the cousins or husbands are selected as the household reference person. The use of standard methods for selecting reference persons will alleviate (but not entirely solve) this problem (see Appendix A of the 'Relationship in household' standard).

The Census is the only collection which to date has published 'Relationship between families' data.