Quality Statement
Housing quality refers to the adequacy of the structure (internal and external) and internal environment of a dwelling. Good quality housing is housing that is suitable for habitation. It provides sufficient shelter and protection from the outside environment, a healthy indoor environment (warm, safe, mould-free, and dry), and contains the amenities needed for everyday living.
Access to basic amenities indicates what basic services and structures (for example, cooking facilities, shower or bath, and electricity) are available inside an occupied private dwelling. The amenities need to be in working order to be counted.
Dwelling dampness indicates whether an occupied private dwelling is not damp (dry throughout) or the degree to which it is damp – sometimes damp or always damp. Dampness is defined as when a dwelling feels or smells damp or has damp patches on the wall, ceiling, floor, or window frames.
Dwelling mould measures the total amount of visible mould inside occupied private dwellings. It indicates whether mould is present (always or sometimes) that has a total area larger than an A4 sheet of paper, or smaller than A4 size or whether there is no mould. It excludes any mould that is not visible, for example, mould inside walls.
Access to basic amenities: Moderate quality
Dwelling dampness indicator: Moderate quality
Dwelling mould indicator: Moderate quality
Data quality processes section below has more detail on the rating.
Priority level 3
A priority level is assigned to all census concepts: priority 1, 2, or 3 (with 1 being highest and 3 being the lowest priority).
Housing quality is a priority 3 concept. Priority 3 concepts are given third priority in terms of quality, time, and resources across all phases of the census. Priority 3 concepts are those that are:
- data that census would not be solely run for, and information about population groups that could not be captured without being in a census
- data that is important to certain groups
- data that can be used to create sampling frames for other surveys.
The census priority level for housing quality remains the same as for the 2018 Census.
The 2023 Census: Final content report has more information on priority ratings for census concepts.
Occupied private dwellings
‘Subject population’ means the people, families, households, or dwellings that the variable applies to.
Access to basic amenities
Access to basic amenities is categorised into the following categories:
Census access to basic amenities V2.0.0 – level 1 of 2
Code | Category |
---|---|
0 | None of these |
1 | Cooking facilities |
2 | Tap water that is safe to drink |
3 | Kitchen sink |
4 | Refrigerator |
5 | Bath or shower |
6 | Toilet |
7 | Electricity supply |
9 | Not elsewhere included |
Access to basic amenities uses a 2-level hierarchical classification with level 1 presented in the table above.
The level 1 residual category ‘Not elsewhere included’ contains the residual categories ‘Response unidentifiable' and 'Not stated'. Follow the link above the table to examine the classification in more detail.
Access to basic amenities is a multiple response variable so the number of responses is greater than the total number of occupied private dwellings.
Number of basic amenities
Number of basic amenities is classified into the following categories:
Census number of basic amenities available V2.0.0 – level 1 of 2
Code | Category |
---|---|
0 | No basic amenities available |
1 | One amenity |
2 | Two amenities |
3 | Three amenities |
4 | Four amenities |
5 | Five amenities |
6 | Six amenities |
7 | Seven amenities |
9 | Not elsewhere included |
Number of basic amenities uses a 2-level hierarchical classification with level 1 presented in the table above.
The level 1 category ‘Not elsewhere included’ contains the residual categories ‘Response unidentifiable' and 'Not stated'. Follow the link above the table to examine the classification in more detail.
Dwelling dampness
Dwelling dampness is categorised into the following categories:
Census dwelling dampness indicator V2.0.0 – level 1 of 2
Code | Category |
---|---|
01 | Always damp |
02 | Sometimes damp |
03 | Not damp |
99 | Not elsewhere included |
Dwelling dampness indicator uses a 2-level hierarchical classification with level 1 presented in the table above.
The level 1 category ‘Not elsewhere included’ contains the residual categories ‘Don’t know’, ‘Response unidentifiable', and 'Not stated'. Follow the link above the table to examine the classification in more detail.
Dwelling mould
Dwelling mould is classified into the following categories:
Census dwelling mould indicator V2.0.0 – level 1 of 2
Code | Category |
---|---|
01 | Mould over A4 size - always |
02 | Mould over A4 size - sometimes |
03 | No mould/mould smaller than A4 size |
99 | Not elsewhere included |
Dwelling mould indicator uses a 2-level hierarchical classification with level 1 presented in the table above.
The level 1 category ‘Not elsewhere included’ contains the residual categories ‘Don’t know’, ‘Response unidentifiable', and 'Not stated'. Follow the link above the table to examine the classification in more detail.
The 2023 Census classifications for access to basic amenities, number of basic amenities, dwelling dampness indicator, and dwelling mould indicator available are consistent with those used in the 2018 Census.
Standards and classifications has more information on what classifications are, how they are reviewed, where they are stored, and how to provide feedback on them.
Data for housing quality is collected from the dwelling form:
- dwelling dampness indicator (question 15 paper form)
- dwelling mould indicator (question 16 paper form)
- access to basic amenities (question 17 paper form).
There were differences in the way a person could respond between the modes of collection (online and paper forms).
On the online form:
- for the damp and mould questions, only one response could be selected, preventing inconsistent responses for the access to basic amenities question. If 'none of these' was marked, any other response was cleared, preventing residual responses.
On the paper form:
- for the damp and mould questions, it was possible to select more than one response
- for the amenities question, it was possible to select none of these and one or more of the amenities boxes.
Data from online forms may therefore be of higher overall quality than data from paper forms. However, processing checks and edits were in place to improve the quality of the paper forms.
Stats NZ Store House has samples for both the individual and dwelling paper forms.
Data-use outside Stats NZ:
- to better understand the state of New Zealand’s housing
- to provide information to help develop community and government initiatives to address housing quality issues
- to understand the relationship between housing quality and health outcomes to inform public health action and help target resources
- to help understand energy hardship in New Zealand
- to help measure the full extent of severe housing deprivation in New Zealand – the data on access to basic amenities indicates whether housing is uninhabitable
- to help create the New Zealand Deprivation Index (NZDep). Dwelling dampness and dwelling mould are two dimensions of deprivation used to create this index.
Data-use by Stats NZ:
- to produce more in-depth reports and analyses on housing such as the Housing in Aotearoa: 2020 report.
The table below shows the distribution of data sources for access to basic amenities data. All data was from census forms as no alternative data sources were available.
Data sources for access to basic amenities data, as a percentage of occupied private dwellings, 2023 Census | ||
---|---|---|
Source of access to basic amenities data | Percent | |
2023 Census response | 91.5 | |
Historical census | 0.0 | |
Admin data | 0.0 | |
Deterministic derivation | 0.0 | |
Statistical imputation | 0.0 | |
No information | 8.5 | |
Total | 100.0 | |
Note: Due to rounding, individual figures may not always sum to the stated total(s) or score contributions. |
The table below shows the distribution of data sources for dwelling dampness indicator data. All data was from census forms as no alternative data sources were available.
Data sources for dwelling dampness indicator data, as a percentage of occupied private dwellings, 2023 Census | ||
---|---|---|
Source of dwelling dampness indicator data | Percent | |
2023 Census response | 91.5 | |
Historical census | 0.0 | |
Admin data | 0.0 | |
Deterministic derivation | 0.0 | |
Statistical imputation | 0.0 | |
No information | 8.5 | |
Total | 100.0 | |
Note: Due to rounding, individual figures may not always sum to the stated total(s) or score contributions. |
The table below shows the distribution of data sources for dwelling mould indicator data. All data was from census forms as no alternative data sources were available.
Data sources for dwelling mould indicator data, as a percentage of occupied private dwellings, 2023 Census | ||
---|---|---|
Source of dwelling mould indicator data | Percent | |
2023 Census response | 91.4 | |
Historical census | 0.0 | |
Admin data | 0.0 | |
Deterministic derivation | 0.0 | |
Statistical imputation | 0.0 | |
No information | 8.6 | |
Total | 100.0 | |
Note: Due to rounding, individual figures may not always sum to the stated total(s) or score contributions. |
Editing, data sources, and imputation in the 2023 Census has more information around how data sources are improved by editing.
Missing and residual responses represent data gaps where respondents either did not provide answers (missing responses) or provided answers that were not valid (residual responses).
Access to basic amenities – percentage of ‘Not stated’ for occupied private dwellings:
- 2023: 8.5 percent
- 2018: 8.0 percent
Dwelling dampness indicator – percentage of ‘Not stated’ for occupied private dwellings:
- 2023: 8.5 percent
- 2018: 8.0 percent
Dwelling mould indicator – percentage of ‘Not stated’ for occupied private dwellings:
- 2023: 8.6 percent
- 2018: 8.1 percent
For output purposes, the residual category responses are grouped with ‘Not stated’ and are classified as ‘Not elsewhere included’.
Access to basic amenities – percentage of ‘Not elsewhere included’ for occupied private dwellings:
- 2023: 8.5 percent
- 2018: 8.1 percent
Dwelling dampness indicator – percentage of ‘Not elsewhere included’ for occupied private dwellings:
- 2023: 11.1 percent
- 2018: 11.0 percent
Dwelling mould indicator – percentage of ‘Not elsewhere included’ for occupied private dwellings:
- 2023: 10.6 percent
- 2018: 10.3 percent
Note that housing quality was a new concept in the 2018 Census.
Overall quality ratings:
- Access to basic amenities: Moderate
- Dwelling dampness indicator: Moderate
- Dwelling mould indicator: Moderate
Data has been evaluated to assess whether it meets quality standards and is suitable for use.
Three quality metrics contribute to the overall quality rating:
- data sources and coverage
- consistency and coherence
- accuracy of responses.
The lowest rated metric determines the overall quality rating.
Data quality assurance in the 2023 Census provides more information on the quality rating scale.
Data sources and coverage:
- Access to basic amenities: Moderate quality
- Dwelling dampness indicator: Moderate quality
- Dwelling mould indicator: Moderate quality
The quality of all the data sources that contribute to the output for the variable has been assessed. To calculate the data sources and coverage quality score for a variable, each data source is rated and multiplied by the proportion it contributes to the total output.
The rating for a valid census response is defined as 1.00. Ratings for other sources are the best estimates available of their quality relative to a census response. Each source that contributes to the output for that variable is then multiplied by the proportion it contributes to the total output. The total score then determines the metric rating according to the following range:
- 0.98–1.00 = very high
- 0.95–<0.98 = high
- 0.90–<0.95 = moderate
- 0.75–<0.90 = poor
- <0.75 = very poor.
Access to basic amenities
For access to basic amenities, the proportion of data received from 2023 Census forms, the lack of alternative data sources, and the high level of ‘No information’ resulted in a score of 0.92, leading to the quality rating of moderate.
Data sources and coverage rating calculation for access to basic amenities and number of basic amenities data, for occupied private dwellings, 2023 Census | |||
---|---|---|---|
Source of access to basic amenities data | Rating | Percent | Score contribution |
2023 Census response | 1.00 | 91.53 | 0.92 |
No information | 0.00 | 8.47 | 0.00 |
Total | 100.00 | 0.92 | |
Note: Due to rounding, individual figures may not always sum to the stated total(s) or score contributions. |
Dwelling dampness indicator
For the dwelling dampness indicator, the proportion of data received from 2023 Census forms, the lack of alternative data sources, and the high level of ‘No information’ resulted in a score of 0.92, leading to the quality rating of moderate.
Data sources and coverage rating calculation for dwelling dampness indicator data, for occupied private dwellings, 2023 Census | |||
---|---|---|---|
Source of dwelling dampness indicator data | Rating | Percent | Score contribution |
2023 Census response | 1.00 | 91.53 | 0.92 |
No information | 0.00 | 8.47 | 0.00 |
Total | 100.00 | 0.92 | |
Note: Due to rounding, individual figures may not always sum to the stated total(s) or score contributions. |
Dwelling mould indicator
For the dwelling mould indicator, the proportion of data received from 2023 Census forms, the lack of alternative data sources, and the high level of ‘No information’ resulted in a score of 0.91, leading to the quality rating of moderate.
Data sources and coverage rating calculation for dwelling mould indicator data, for occupied private dwellings, 2023 Census | |||
---|---|---|---|
Source of dwelling mould indicator data | Rating | Percent | Score contribution |
2023 Census response | 1.00 | 91.45 | 0.91 |
No information | 0.00 | 8.55 | 0.00 |
Total | 100.00 | 0.91 | |
Note: Due to rounding, individual figures may not always sum to the stated total(s) or score contributions. |
Consistency and coherence:
- Access to basic amenities: High quality
- Dwelling dampness indicator: High quality
- Dwelling mould indicator: High quality
The housing quality data is consistent with expectations across nearly all consistency checks, with some minor variations from expectations or benchmarks that make sense due to real-world change, incorporation of other sources of data, or a change in how the variable has been collected.
The high proportion of missing information means the data may not accurately reflect housing quality for all groups of interest, or all geographic areas, such as Hawkes Bay and Northland which were impacted by severe weather events in 2023. Areas and population groups with greater non-response may mean that the count and proportion of dwellings that are damp, mouldy, or lack access to some basic amenities will be under-represented in the data.
Additionally, visible mould may be easier to report than dampness. There may be a small amount of under-reporting of dampness in the data because some people may not be aware of this in their home.
Reductions in reported levels of dwelling dampness and mould since the 2018 Census may have been partly due to The Healthy Housing Act 2019. This introduced minimum standards for heating, insulation, ventilation, moisture ingress and drainage, and draught stopping in rental properties.
Accuracy of responses ratings:
- Access to amenities: Very high quality
- Dwelling dampness indicator: Very high quality
- Dwelling mould indicator: Very high quality
The housing quality data has no data quality issues that have an observable effect on the data. The quality of the coding is very high. Any issues with the variable appear in a very low number of cases (typically less than a hundred).
The type of form a respondent used (paper or online, English or bilingual) did not influence their response to the questions. Improvements in scanning repair for paper forms improved coding accuracy.
Housing quality data can be used in a comparable manner to the 2018 Census.
When using this data, users should be aware that:
- at all geographic levels, the proportion of ‘Not stated’ has increased since the 2018 Census, particularly in areas impacted by severe weather events in 2023, such as Hawkes Bay, Gisborne, and Northland. This may result in the counts and proportion of dwellings with housing quality issues being under-represented in the data.
- the high proportion of missing information means the data may not provide an accurate picture of housing quality for all groups of interest, particularly Māori and Pacific peoples households who have poorer access to basic amenities and higher rates of non-response.
- the timing of data collection can affect how people respond to questions on dampness and mould. The early March timing of the census may reduce reports of dampness and mould and increase responses of ‘Don’t know’ by respondents who have moved recently and have not yet experienced a winter in their current home.
- the data does not provide any indication of housing quality in non-private dwellings such as boarding houses, residential care for older people, marae, or other types of non-private dwellings in which people live.
Comparisons to other data sources
The census is the only comprehensive source of information about access to basic amenities. Although there are surveys other than census that collect dwelling mould and dampness data, data users are advised to familiarise themselves with the strengths and limitations of these sources before use.
Key considerations when comparing housing quality data from the 2023 Census with other sources include:
- Census is a key source of information on housing quality for small areas and small populations. Many other sources of information do not provide detail at this level.
- The census aims to provide housing quality data for all private occupied dwellings, while other sources such as the New Zealand General Social Survey – Housing module (NZGSS) only collects mould and dampness data from a sample of dwellings.
To assess how this concept aligns with the variables from the previous census, use the link:
- Housing quality: dwelling dampness, mould, and access to basic amenities – 2018 Information by variable
- Data on housing quality was not collected in 2013.
Contact our Information centre for further information about using this concept.