Quality Statement
Activity limitations is determined by the level of difficulty a person perceives themselves as having with six basic universal activities. The six activities are:
- difficulty seeing, even if wearing glasses
- difficulty hearing, even if using a hearing aid
- difficulty walking or climbing steps
- difficulty remembering or concentrating
- difficulty washing all over or dressing
- difficulty communicating using your usual language.
These six questions on activity limitations are known as the Washington Group Short Set on Functioning (WG-SS). In designing this question set, the Washington Group intended that a disability indicator be derived from the six responses combined.
The disability indicator was not designed to identify all disabled people in the population. Rather, it would allow comparisons to be made between average outcomes for disabled and non-disabled populations.
The questions can also be used separately as indicators of the level of difficulty a person has with each activity. The assessment of difficulty might be made by the person filling in the census form rather than the person to whom it refers.
As these six questions do not identify all disabled people, census data should not be used for disability prevalence. The 2023 Household Disability Survey should be used for prevalence instead because, unlike census, it intends to identify all disabled people rather than just a subgroup.
Activity limitations: The level of difficulty a person reports for each of the six activities.
Disability indicator: A person is counted as disabled if they report ‘A lot of difficulty’ or ‘Cannot do at all’ for one or more of the six activities.
Poor 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).
Activity limitations 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 activity limitations remains the same as 2018.
The 2023 Census: Final content report has more information on priority ratings for census concepts.
Census usually resident population count aged 5 years and over
‘Subject population’ means the people, families, households, or dwellings that the variable applies to.
Each of the six activities in the activity limitations concept are classified into the following categories:
Activity limitations V2.2.0 - level 1 of 2
Code | Category |
---|---|
01 | No difficulty |
02 | Some difficulty |
03 | A lot of difficulty |
04 | Cannot do at all |
99 | Not elsewhere included |
Disability indicator data is classified into the following categories:
Census Disability Indicator V4.0.0 - level 1 of 2
Code | Category |
---|---|
00 | Not disabled |
01 | Disabled |
99 | Not elsewhere included |
Both activity limitations and disability indicator use 2-level hierarchical classifications with the level 1 categories presented in the tables above. Follow the links in the tables to examine the classifications.
For both classifications the level 1 residual category ‘Not elsewhere included’ contains the residual categories ‘Response unidentifiable’ and ‘Not stated’.
The disability indicator’s residual responses are:
- ‘Not stated’ only if all six activity limitations responses are classified as ‘Not stated’.
- ‘Response unidentifiable’ if each of the six activity limitations responses are either ‘Response unidentifiable’ or a combination of ‘Response unidentifiable’ and ‘Not stated’.
Activity limitations is also output through Activity limitations – Combined Hierarchy V1.0.0.
Respondents may have multiple activity limitations. As a result the total across all categories may be more than 100 percent for the combined hierarchy classification.
The 2023 Census classification for the six activities and disability indicator are consistent with that 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.
Activity limitations data is collected from the individual form (question 22 on the paper form).
There were differences in question layout, and the way a person could respond between the modes of collection (online and paper forms).
On the online form:
- questions were presented individually. For example, "Do you have difficulty seeing, even if wearing glasses?”
- built-in routing directed people in the subject population to the appropriate questions. Those under five years old and overseas visitors could not answer the activity limitations questions
- only one response could be chosen from the options presented. If a different response was selected, the previous response would automatically disappear.
On the paper form:
- the question asked ‘Do you have difficulty with any of the following?’, then listed the six activities with tick boxes for each activity
- overseas visitors and respondents filling the form out on behalf of children under five years old were directed not to answer the activity limitation questions, but were able to do so
- multiple responses to the single answer disability questions were possible. For example, ticking both ‘No difficulty’ and ‘A lot of difficulty’. These responses are coded to ‘response unidentifiable’
- the bilingual form contained a grid format whereas the English form listed the difficulties.
Data from the 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:
- by government agencies and community groups to monitor the outcomes of disabled people compared with non-disabled people
- to highlight the need for, and support the development of, accessible services
- to inform reports for the New Zealand Disability Strategy and the United Nations Convention on the Rights of Persons with Disabilities.
Data-use by Stats NZ:
- to inform the selection of a sample for the 10-yearly post-census Household Disability Survey (most recently held in 2023).
The table below shows the distribution of data sources for disability indicator data. All data was from census forms as no alternative data sources were available.
Data sources for disability indicator data, as a percentage of census usually resident population count aged 5 years and over, 2023 Census | ||
---|---|---|
Source of disability indicator data | Percent | |
2023 Census response | 85.0 | |
Historical census | 0.0 | |
Admin data | 0.0 | |
Deterministic derivation | 0.0 | |
Statistical imputation | 0.0 | |
No information | 15.0 | |
Total | 100.0 | |
Note: Due to rounding, individual figures may not always sum to the stated total(s) or score contributions. |
For each activity limitation, the level of information sourced from 2023 Census responses is similar:
- difficulty seeing: 84.7 percent
- difficulty hearing: 84.5 percent
- difficulty walking: 84.5 percent
- difficulty remembering: 84.5 percent
- difficulty washing: 84.5 percent
- difficulty communicating: 84.5 percent.
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).
Percentage of ‘Not stated’ for the census usually resident population count aged 5 years and over:
Disability indicator
- 2023: 15.0 percent
- 2018: 16.0 percent
For each of the activity limitation input variables, the percentage coded to ‘Not stated’ for 2023 Census was:
- difficulty seeing: 15.3 percent
- difficulty hearing: 15.5 percent
- difficulty walking: 15.5 percent
- difficulty remembering: 15.5 percent
- difficulty washing: 15.5 percent
- difficulty communicating: 15.5 percent
For output purposes, the residual category responses are grouped with ‘Not stated’ and are classified as ‘Not elsewhere included’.
Percentage of ‘Not elsewhere included’ for the census usually resident population count aged 5 years and over:
Disability indicator
- 2023: 15.1 percent
- 2018: 16.0 percent
For each of the activity limitation input variables, the percentage coded to ‘Not elsewhere included’ for 2023 Census was:
- difficulty seeing: 15.5 percent
- difficulty hearing: 15.6 percent
- difficulty walking: 15.6 percent
- difficulty remembering: 15.6 percent
- difficulty washing: 15.6 percent
- difficulty communicating: 15.6 percent
Overall quality rating: Poor
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: Poor quality
The quality of all the data sources that contribute to the output for the variable were 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.
Due to a lack of alternative sources available for this concept, and the level of ‘No information’, disability indicator has a data sources and coverage rating of poor.
Data sources and coverage rating calculation for disability indicator data, census usually resident population count aged 5 years and over, 2023 Census | |||
---|---|---|---|
Source of disability indicator data | Rating | Percent | Score contribution |
2023 Census response | 1.00 | 84.97 | 0.85 |
No information | 0.00 | 15.03 | 0.00 |
Total | 100.00 | 0.85 | |
Note: Due to rounding, individual figures may not always sum to stated total(s) or score contributions. |
Consistency and coherence: High quality
Activity limitations and disability indicator data is consistent with expectations across nearly all consistency checks, with some minor variation from expectations or benchmarks which makes sense due to real-world change, incorporation of other sources of data, or a change in how the variable has been collected.
While the data is very consistent with data from the 2018 Census, the high proportion of missing information means that the data may not present an accurate representation of activity limitations for all groups of interest. This is especially true for Māori and Pacific peoples, who have higher levels of difficulty as well as higher rates of non-response to the census.
Accuracy of responses: High quality
Activity limitations and disability indicator data has only minor data quality issues. The quality of coding and responses within classification categories is high. Any issues with the variable appear in a low number of cases (typically in the low hundreds).
Activity limitations data is comparable to the 2018 Census, when the current question was introduced.
When using this data, users should be aware that:
- While activity limitations received a quality rating of poor, this is only due to the census response rate and the lack of alternative data sources. There are biases in the non-responding population, however the data is otherwise of high quality. Care is advised when interpreting results due to this high level of missing responses.
- The disability indicator and activity limitation variables do not provide an official count or prevalence rate of disabled people in New Zealand. Any counts or prevalence rates that come from the 2023 Census will be an undercount of the true disabled population because the disability indicator and activity limitation variable do not identify all disabled people. Instead, the official prevalence estimate is taken from the 2023 Household Disability Survey which contains a longer and much more inclusive set of questions about activity limitations and functional difficulties than just the six census questions.
- The disability indicator may be used to examine and compare socio-economic outcomes of disabled and non-disabled people using proportions. Using counts is not advised because this variable undercounts disabled people.
- All six activity limitations may be used individually when examining outcomes for disabled people with specific impairments. Users should be aware that one question alone is not suitable to identify the disabled population with specific impairments, but this data can be used in the absence of other sources.
- The disability indicator groups those with ‘no difficulty’ and ‘some difficulty’ as ‘not disabled’. As such, changes between ‘no difficulty’ and ‘some difficulty’ are not evident in the disability indicator.
- Care is advised when using the disability indicator and activity limitation variables for small geographies. For small geographies, there will be variability in the percentage of missing data for a given area. This means some small geographic areas will have poorer quality data than the overall quality rating.
- Māori, Pacific peoples, those living in rural areas and unemployed have higher proportions of missing data than the overall subject population. These populations also tend to have higher disability rates.
Comparisons to other data sources
The 2023 Census uses an unaltered version of the Washington Group Short Set on Functioning (WG-SS) that is consistent with the 2018 Census. Other surveys that also use this version are Te Kupenga, the General Social Survey, and the Household Labour Force Survey.
Care should be taken when comparing 2023 Census disability data with other sources that do not use the WG-SS or use additional measures to measure the disabled population. Comparisons between census data and the Household Disability Survey (HDS) are not recommended because the method used to identify disabled people and the resulting data is different. The census only intends to find a subgroup of disabled people and to then use this subgroup to compare socio-economic outcomes between disabled and non-disabled people.
The HDS provides the official prevalence estimate of all disabled people in New Zealand, so it uses a much more comprehensive question set with the intention of identifying all disabled people within its sample. There are other differences too, such as when there is an HDS question that is equivalent to one of the six census activity limitations questions, often the wording differs slightly, and the HDS instructs respondents to only report on difficulties that are caused by a long-term condition or health problem; census activity limitations questions do not specify that limitations should be long-term.
To assess how this concept aligns with the variables from the previous census, use the link below:
- Activity limitations – 2018 Information by variable
- An activity limitations information by variable was not published in 2013.
Contact our Information centre for further information about using this concept.