Household composition 2013 Census (information about this variable and its quality)

##Related variables

• Number of usual residents in household
• Number of usual residents aged 15 and over in household
• Number of usual residents aged under 15 in household
• Age of youngest child in household
• Age of youngest dependent child in household
• Household composition by child dependency status
• Number of dependent children in household

##Where the data comes from

The key questions from which this variable (and related variables) is derived are questions 6 (relationship to reference person) and 21 (absentee relationship to reference person) on the dwelling form and question 19 (living arrangements) on the individual form.

##How this data is classified

1 One-family household (with or without other people)

2 Two-family household (with or without other people)

3 Three or more family household (with or without other people)

4 Other multi-person household

5 One-person household

6 Household composition unidentifiable

More detailed information is available at lower levels of this classification.

For further information about this classification, refer to the:

• 2013 Census data dictionary
• Statistical standard for household composition.

For background information on classifications and standards, refer to the Classifications and related statistical standards page.

##Subject population

The subject population for this variable are households in private occupied dwellings (visitor-only private dwellings are excluded).

The subject population is the people, families, households, or dwellings to whom the variable applies.

##Non-response and data that could not be classified

In 2013, 2.6 percent of households were classified as 'Household composition unidentifiable', compared with 1.9 percent in 2006 and 2.1 percent in 2001.

##How this data is used

Data from this variable (and related family and household variables) is used:

• by central government agencies, local authorities, private organisations, and researchers in the formulation of social policy, for planning and monitoring programmes, and for research purposes
• by Statistics New Zealand to derive household and family projections
• in developing the New Zealand Deprivation Index.

##Data quality processes

All census data was checked thoroughly during processing and evaluation, to ensure that it met quality standards and is suitable for use. These quality checks included edits.

All data must meet minimum quality standards to make it suitable for use.

Quality level

A quality level is assigned to all census variables: foremost, defining, or supplementary.

Household composition is a defining variable. Defining variables cover key subject populations that are important for policy development, evaluation, or monitoring. These variables are given second priority in terms of quality, time, and resources across all phases of a census.

Mode of collection impacts – online form compared with paper form

The online forms had built-in editing functionality that directed respondents to the appropriate questions and ensured that their responses were valid. As a result of this, data from online forms may be of higher overall quality than data from paper forms. The significance of this will depend on the particular type of analysis being done. There will always be a mode effect but this cannot be measured. Statistics NZ design and test to minimise the effects of mode for all questions.

There were differences between how the forms were completed online and on paper for this variable:

• On the online form, only one response could be selected for each person's relationship to the reference person in questions 6 and 21 on the dwelling form. Multiple responses for a person's relationship to the reference person were possible when forms were completed on paper.
• For the living arrangements question, the online form did not allow the inconsistent multiple response of 'I live alone' to be selected at the same time as one or more responses indicating people who the respondent lived with. If the 'I live alone' box was marked, any other responses to living arrangements disappeared. Inconsistent multiple responses to this question were possible when forms were completed on paper.

##Quality assessment of data and data quality issues for this variable

Overall quality assessment

High: fit for use – with minor data quality issues only. 2013 Census variable quality rating scale gives more detail.

Issues to note

• There is a slightly higher percentage of households whose composition is unidentifiable compared with previous censuses.

##Comparing this data with previous census data

The household composition data for 2013 is comparable with that from the 2006 and 2001 Censuses. While the output classification is new, changes from the classification used in 2006 and 2001 were minor and limited to descriptors. Changes in the data over this time period can be interpreted as real changes because there have been only very minor change in the way the data has been collected, defined, and classified.

##Comparing this data with data from other sources

Census is the only information source that provides comprehensive information for small areas and small populations. However alternative sources of information about this subject are available:

• Household Labour Force Survey (HLFS)
• New Zealand General Social Survey (NZGSS)
• Household Economic Survey (HES)
• National and Subnational Family and Household Projections

Data from these alternative sources may show differences from census data for several reasons. These could be due to differences in scope, coverage, non-response rates, data being collected at different periods of time, alternative sources being sample surveys and as such subject to sampling errors, or differences in question wordings and method of delivery (self-administered versus interviewer-administered). Data users are advised to familiarise themselves with the strengths and limitations of individual data sources before comparing with census data.

Census data is used as the baseline for population projections so the accuracy of the projections tends to deteriorate with time elapsed after the census date.

##Further information about this data

All percentages in census publications have been calculated using 'Total stated' as the denominator.

When using this data, be aware of the following:

• During census processing, the people in each private dwelling (including absentees) have codes allocated to them that indicate who they live with and their roles within families (eg partner, parent, child). This is called family coding. The household composition derivation uses the family coding to identify family nuclei and related people within households and to determine the composition of each household.
• There are a small number of one-person households for which the sole resident is aged under 15 years. This is primarily due to respondent error.
• There has been no significant change to the household data that can be attributed to the longer than usual time period between censuses.

Contact our Information Centre for further information about using this variable.