Activity limitations (information about this variable and its quality)

Priority level

Priority level 3

We assign a priority level to all census variables: Priority 1, 2, or 3 (with 1 being highest and 3 being the lowest priority).

Activity limitations is a priority 3 variable. Priority 3 variables do not fit in directly with the main purpose of a census but are still important to certain groups. These variables are given third priority in terms of quality, time, and resources across all phases of a census.

Quality Management Strategy has more information on the priority rating.

Overall quality rating for 2018 Census

Poor quality

Data quality processes section below has more detail on the rating for this variable.

The External Data Quality Panel has commented on the quality of this variable. Final report of the 2018 Census External Data Quality Panel has more information.

Caution is advised when using this variable at small geographies. Please see Recommendations for use and further information section below

Subject population

Census usually resident population aged 5 years and over

‘Subject population’ means the people, families, households, or dwellings to whom the variable applies.

How this data is classified

Activity limitationsV2.2.0

Activity limitations is a flat classification with the following categories for each of the six activities:

01 No difficulty

02 Some difficulty

03 A lot of difficulty

04 Can't do at all

99 Not elsewhere included

‘Not elsewhere included’ contains the residual categories of ‘response unidentifiable’ and ‘not stated’.

Census Disability IndicatorV4.0.0

The disability indicator is derived from responses to the six activity limitation indicators. It is a flat classification with the following categories:

00 Not disabled

01 Disabled

99 Not elsewhere included

‘Not elsewhere included’ contains the residual categories of ‘response unidentifiable’ and ‘not stated’.

Explanatory note

• The activity limitation questions are used to derive the disability indicator. The Washington Group further explains the output categories and options.
• To be counted as disabled (and therefore classified as ‘1 Disabled' for the disability indicator), a respondent must have indicated that they experience ‘a lot of difficulty’ or ‘cannot do at all’ one or more of the six activity limitation questions.

The Standards and Classifications page provides background information on classifications and standards.

Question format

Activity limitations is collected from six questions on the individual form (question 22 on the paper form).

Stats NZ Store House has samples for both the individual and dwelling paper forms.

There were differences in question format and wording between the modes of collection (online and paper forms):

• on the paper form the question stated ‘do you have difficulty with any of the following’ then listed the six activities
• on the online form, the questions were presented individually, for example: “do you have difficulty seeing, even if wearing glasses?”

There were also differences in the way a person could respond between the online and paper versions of this question.

On the online individual form:

• built-in routing directed people in the subject population to the appropriate questions. Those under 5 and overseas visitors could not answer the qualifications questions.
• the activity limitations questions had to be answered with a single response per question.

On the paper individual form:

• multiple responses to the single answer disability questions were possible, for example ticking both “no difficulty” and “a lot of difficulty”. These responses were coded to ‘response unidentifiable’.

How this data is used

Outside Stats NZ

• Activity limitations data can be used by government agencies and community groups to monitor the outcomes of disabled people compared with non-disabled people and to inform reports for the New Zealand Disability Strategy and the UN Convention on the Rights of Persons with Disabilities.

Within Stats NZ

• Previously, disability data from the census were not output by Stats NZ. They were used to inform the selection of a sample for the Household Disability Survey.
• To compare socio-economic outcomes for disabled people with those for non-disabled people.

2018 data sources

No alternative data source or imputation was used to replace missing responses or responses that could not be classified for activity limitations.

The ‘no information’ percentage is where we were not able to source activity limitations data for a person in the subject population and so were not able to derive their disability indicator status.

Please note that when examining activity limitations data for specific population groups within the subject population, the no information percentage may differ from that for the overall subject population.

Missing and residual responses

‘No information’ in the data sources table, is the percentage of the subject population coded to ‘not stated’. In previous censuses, non-response was the percentage of the subject population coded to ‘not stated.’ As this variable was not measured or output in the same way for previous censuses, only 2018 figures are presented below.

Percentage of ‘not stated’ for the census usually resident population aged 5 years and over:

• 2018 Disability indicator: 16.0 percent.

This figure is the percent of the subject population that did not respond to any of the six activity limitation input variables.

For each of the activity limitation input variables, the percent coded to not stated were:

• Difficulty seeing: 16.3 percent
• Difficulty hearing: 16.6 percent
• Difficulty walking: 16.5 percent
• Difficulty remembering: 16.5 percent
• Difficulty washing: 16.5 percent
• Difficulty communicating: 16.3 percent.

Responses that could not be classified or did not provide the type of information asked for (response unidentifiable) remain in the data, as there were no alternative data sources available to replace them. In the data sources table, these residuals are included in the ‘Response from 2018 Census’ percentage.

Percentage of ‘not elsewhere included’ for the census usually resident population aged 5 years and over:

• Difficulty seeing: 16.5 percent
• Difficulty hearing: 16.8 percent
• Difficulty walking: 16.6 percent
• Difficulty remembering: 16.6 percent
• Difficulty washing: 16.6 percent
• Difficulty communicating: 16.4 percent.

Data quality processes

Overall quality rating: Poor quality

Data was evaluated to assess whether it meets quality standards and is suitable for use.

Three quality metrics contributed to the overall quality rating:

• data sources and coverage
• consistency and coherence
• data quality.

The lowest rated metric determines the overall quality rating.

Data quality assurance for 2018 Census provides more information on the quality rating scale.

Data sources and coverage: Poor quality

We have assessed the quality of all the data sources that contribute to the output for the variable. As no alternative data sources or imputation were used to replace missing responses, the final metric 1 quality rating for activity limitations reflects the lower than expected response to the census overall, the percentage of individuals who were admin enumerated, and the percentage that did not answer the activity limitations question.

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:

• 98–100 = very high
• 95–<98 = high
• 90–<95 = moderate
• 75–<90 = poor
• <75 = very poor.

The low proportion of data from received forms therefore contributed to the score of 0.84, determining the poor quality rating.

Consistency and coherence: High quality

As this is a new variable, there is no available census data for comparison with 2013 and 2006. Previous censuses had questions on disability, however these were significantly different from the questions used in 2018 and were used to determine the sample for the Disability Survey. The 2013 Disability Survey has more information.

However, the activity limitations data is consistent with expectations across nearly all consistency checks, with some minor variation from expectations or benchmarks that makes sense due to real-world change, or a change in how the variable has been collected.

The disability indicator is consistent with expectations at a national level and is mostly consistent across regional councils.

Data quality: High quality

The data quality checks for activity limitations included edits for consistency within the dataset and cross-tabulations to the regional council level of geography.

Activity limitations data has only minor data quality issues. The quality of coding and responses within classification categories is high. Any impact of other data sources used is minor. Any issues with the variable appear in a low number of cases (typically in the low hundreds).

Recommendations for use and further information

As activity limitations is a new output variable in 2018 and has a high rate of missing responses with no alternative data sources, some caution is advised when using this variable:

• the disability indicator and activity limitation variable is not intended to provide an official count or prevalence rate of people in New Zealand with disabilities. The official count is currently taken from the NZ Disability Survey which contains more questions about activity limitations and functional difficulties than the six census questions.
• the disability indicator may be used to examine and compare proportions of socio-economic outcomes of people with a disability and those without. Using total counts is not advised for this variable.
• all six activity limitations may be used when examining outcomes for those with limitations compared to those without limitations. Users should be aware that one question alone is not ideal to identify total counts of people with a specific disability, but this data can be used in the absence of other sources. Caution is advised when interpreting results due to the high level of missing responses.
• caution is advised when using the disability indicator and activity limitation variables at small geographies. At small geographies, there will be variability in the percentage of missing data for a given area. This means some small geography areas will have poorer quality data than the overall quality rating. Ōpōtiki, Kawerau, Far North and Wairoa districts have higher rates of non-response than the overall subject population.
• Māori, Pacific peoples, respondents aged 20–29, and unemployed have higher proportions of missing data than that of the overall subject population.

Contact our Information Centre for further information about using this variable