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Disability Survey: 2013
Embargoed until 10:45am  –  17 June 2014
Data quality

Period-specific information
This section contains data information that has changed since the last release.

General information 
This section contains information that does not change between releases.

Period-specific information

Reference period

The data collection took place over 11 weeks, from 24 July 2013 to 10 October 2013. Collection for the Household Disability Survey (HDS) took place from 24 July to 7 October, and for the Disability Survey of Residential Facilities (DSRF) from 26 August to 10 October.

Response rate

The target response rates for the HDS and DSRF were 80 and 90 percent, respectively.

The HDS achieved an 82 percent response rate, with our minimum target of 4,000 disabled people reached. The DSRF survey achieved a response rate of 93 percent.

The response rate is the estimated number of eligible people who responded to the survey, divided by the estimated number of eligible people, and expressed as a percentage.

Change due to the 22 February 2011 earthquake

This survey was originally planned for 2011 but due to the earthquakes in Canterbury, the Disability Survey was postponed along with the 2011 Census until 2013.

Comparability with data from the 2006 survey

The 2006 survey reported a significant decline in the disability rate (17 percent) compared with that reported in earlier surveys (the 2001 and 1996 rates were both 20 percent). The 2006 information release advised people to be cautious when comparing the 2006 disability rate with disability rates from previous surveys, particularly for the adult household rate. This recommendation also applies to comparisons of 2006 with 2013 disability rates. In this release, we have compared disability rates with 2001 only.

For more information see ‘Comment on the apparent decline in the disability rate’ in the technical notes of the 2006 information release.

Changes to survey content

The content of the disability survey was relatively unchanged between the 1996, 2001, and 2006 surveys. A key aim in redeveloping the 2013 survey was to update the content to produce the best-possible estimates of disability prevalence and to ensure the statistics are relevant to current and emerging needs.

The New Zealand Government ratified the United Nations Convention on the Rights of Persons with Disabilities in 2008. Obligations to report against this convention led to some changes in the content of the 2013 Disability Survey compared with 2006.

During 2008, we consulted a range of groups and individuals representing the disabled community, to identify priority needs for the content of the 2011/2013 survey.

For more information about this review see the 2011 Disability Survey: Discussion paper on proposed content.

Definition of ‘disability’

In previous surveys, we used a functional concept of disability: ‘any restriction or lack (resulting from impairment) of ability to perform an activity in the manner or within the normal range considered normal for a human being.’

For the 2013 Disability Survey, we defined a disability as: ‘an impairment which has a long-term limiting effect on a person’s ability to carry out day-to-day activities. Long-term means six months or longer and limiting effect means a restriction or lack of ability to perform.’

Questionnaire content

The following changes have resulted from the redevelopment of the 2013 Disability Survey:

  • the questions focusing on main conditions or health problems causing difficulties were not included
  • less detail was collected on the use of assistive devices
  • a series of questions relating to social outcomes were included
  • the screening questions used to define whether a child is disabled or non-disabled have been changed to more closely align with the adult screening questions. This means that data for children from the 2013 survey is not directly comparable with previous disability surveys.

The 2013 Disability Survey includes new information about social outcomes. We collected information about leisure activities and carers of children in the 2013 children questionnaire. We collected information about feelings of safety, experience of crime, social contact, and access to leisure activities in the 2013 adult household questionnaire.

Other changes related to output variables

Ethnic group
For earlier surveys, ethnic group was prioritised. This means we categorised the ethnicity of a person who identified with more than one ethnic group to a single group.

The order of prioritisation was Māori, Pacific, Asian, Other, and European. For example, a person who identified as Māori and Samoan would be categorised as Māori. A person who identified as New Zealand European and Samoan would be categorised in the Pacific ethnic group.

For the 2013 survey, we categorised ethnicity using grouped total responses. In this method, a person who identifies with more than one ethnic group is counted once in each group. For example, at level one of the ethnic group classification, a person of Samoan, Tongan, and German ethnicity would be counted once in the Pacific ethnic group and once in the European ethnic group.

Disability data on the Māori population is the only ethnic-group data that is consistent over time. Ethnic data from the 2013 survey is not comparable with previous disability surveys.

Reclassification of agility questions

In previous surveys, the following questions were classified as ‘agility’ impairments:

  1. When standing, can you bend down and pick something up off the floor, for example a shoe?
  2. Can you get in and out of bed by yourself? If answered ‘no’, then asked: Is this because of a long-term condition or health problem?

For the 2013 survey, these questions have been classified as ‘mobility’ impairments.

Be cautious when comparing agility and/or mobility data, as these impairment types are not comparable over time.

Changes to census disability questions

We used census data to form the sample frame for the Household Disability Survey. To make sure we included enough disabled people, the sample selection relies on responses to two census questions about disability. We changed the relevant census questions for the 2013 Census to better identify disabled people for the sample selection.

2013 Census disability questions:

Q16: Does a health problem or a condition you have (lasting six months or more) cause you difficulty with, or stop you from:

  • seeing, even when wearing glasses or contact lenses
  • hearing, even when using a hearing aid
  • walking, lifting, or bending
  • using your hands to hold, grasp, or use objects
  • learning, concentrating, or remembering
  • communicating, mixing with others, or socialising, or
  • no difficulty with any of these.

Q17: Do you have a long-term disability (lasting six months or more) that stops you from doing everyday things other people can do?

  • Yes
  • No

2006 Census disability questions: 

Q16: Does a health problem or a condition you have (lasting six months or more) cause you difficulty with, or stop you doing:

  • everyday activities that people your age can usually do
  • communicating, mixing with others, or socialising
  • any other activity that people your age can usually do, or
  • no difficulty with any of these.

Q17: Do you have any disability or handicap that is long-term (lasting six months or more)?

  • Yes
  • No

Changes to survey sample

Household Disability Survey (HDS)

The 2001 and 2006 HDS samples included a 10,000 oversample of Māori and Pacific peoples, contributing to a total sample of 40,000. In the 2013 survey there was no oversample for Pacific people, and an oversample of 2,000 for Māori, contributing to a total sample size of 23,000.

For the 2001 and 2006 surveys, we included group homes (with fewer than 10 people) in the HDS. For 2013, we included group homes with fewer than five people in the sample for the HDS.

Disability Survey of Residential Facilities (DSRF)

Whereas the 2001 and 2006 survey samples included facilities with 10 or more long-stay beds, the 2013 survey includes facilities with as few as five long-stay beds. This change has meant that more psychiatric-type care only facilities are now included in the sample for the DSRF because these types of facilities usually have fewer than 10 beds.

Release of embargoed data

In March 2014, we received a special and urgent data request from the Ministry of Health for embargoed provisional data from the 2013 Disability Survey. The data required was to inform their minister on policy-cost estimates for funded family care of disabled people.

It is only under exceptional circumstances that we allow access to data prior to the official embargoed release date. A strict process was followed to determine the risk of providing this data and the value for the Ministry of Health’s project. The following factors informed the decision:

  • the Ministry of Health agreed to abide by all restrictions around access and use of the data to ensure the confidentiality of the data supplied
  • the data supplied is only a very small part of the survey
  • the data requested was not a key survey output
  • the data requested was not market sensitive.

For these reasons, we released the data to the Ministry of Health before the public release of data on 17 June 2014.

General information 

Target population

The target population for 2013 Household Disability Survey is the usually resident population of New Zealand, living in occupied private dwellings or group homes on the night of the 2013 Census of Population and Dwellings.

The usually resident population excludes:

  • non-New Zealand diplomats and non-New Zealand members of their staff and households
  • members of non-New Zealand armed forces stationed in New Zealand and their dependants
  • overseas visitors who have been resident in New Zealand for less than 12 months and who do not intend to stay in New Zealand for a total period of more than 12 months.

Occupied private dwellings can be permanent or temporary dwellings that are occupied by a person or group of people and are not available for public use. The main purpose of a private dwelling is as a place of habitation, and it is usually built (or converted) to function as a self-contained housing unit. This includes:

  • separate houses
  • flats/units and apartments that are self-contained in respect of sleeping, cooking, dining, bathing, and toilet facilities
  • motor camps
  • tents
  • caravans
  • campervans
  • boats.

The target population for the 2013 Disability Survey of Residential Facilities is the usually resident population of New Zealand aged 15 years and over living in residential care facilities (or occupied non-private dwellings) on the night of the 2013 Census of Population and Dwellings.

Occupied non-private dwellings provide short- or long-term communal or transitory-type accommodation. They are generally available to the public for reasons of employment, study, special need, legal requirement, or recreation. Examples of occupied non-private dwellings include hospitals, hotels, motels, and boarding houses.

A residential care facility is a non-private dwelling being one of:

  • rest home (standard-level care or dementia)
  • continuing care hospital (geriatric or psycho-geriatric)
  • disability units (intellectual, physical, sensory, psychiatric, or multi-disability).

Survey population

The survey population for the HDS is the usually resident population of New Zealand, staying in occupied private dwellings and group homes (with fewer than five people) on the main islands of New Zealand (North, South, and Waiheke) on the night of the 2013 Census (5 March 2013).

The survey population for the DSRF is people aged 15 years and over, and living in rest homes, occupying long-stay beds in continuing care hospitals, or living in long-stay residential units for people with intellectual and/or physical impairments (with five or more people).

Collection methods

Interview methods

We collected information for the survey by trained interviewers either by Computer Assisted Telephone Interview (CATI) or face-to-face through Computer Assisted Personal Interview (CAPI).

For the HDS, we carried out 90 percent of interviews by CATI and 10 percent face-to-face (CAPI). Collection for the DSRF was solely by face-to-face interviews (CAPI).

People selected for the HDS were automatically allocated to a CAPI interview if:

  • they had no telephone contact number on their 2013 Census form
  • they indicated on their census form that they had a hearing impairment.

Options were available to access services such as sign language interpreters and NZ Relay Service to help respondents complete the survey. One interview was completed using a sign language interpreter.

Proxy

For children (0–14 years), an adult (parent, guardian, or caregiver) answered the survey questions on behalf of the selected child.

Where possible, we interviewed the selected adults. If a selected adult could not answer the questions due to a health condition or disability, another adult (usually a caregiver or guardian) answered the questions on their behalf.

Interviewing of individuals living in residential facilities involved a signed consent form.

Survey methodology

Survey design

The 2013 Disability Survey was a post-censal survey. A post-censal survey provides a unique opportunity to run a large survey of a small subgroup of the population in a cost-effective manner. Administrative lists, such as the electoral roll, suffer from serious undercoverage, and using the Statistics NZ household survey frame is expensive because of the need to screen many households to find the target population. Using the 2013 Census as a frame provided a degree of coverage not matched by any other single method.

In addition, information collected in the 2013 Disability Survey was linked with census responses to questions such as income and labour force status. This minimises the burden on respondents and helps to reduce data collection costs.

Sample design

The two surveys making up the Disability Survey (HDS and DSRF) had different sample designs.

Sample design for HDS

The HDS used information from the 2013 Census to create a frame (or list) from which to draw the sample. Formation of the sample frame is made possible by including two disability questions in the census.

The sample selection for the HDS is conducted in three stages:

  1. selecting primary sampling units (PSU) from the Household Survey Frame
  2. selecting people within PSUs and stratum
  3. random subsampling of one person per household where more than one person was selected.

At the first stage, we select a sample of PSUs from the Household Survey Frame (HSF). A primary sampling unit (PSU) is a small geographic area made up of meshblocks and aims to contain a standard number of permanent private dwellings as much as possible. The HSF is the standard sampling frame we use to select samples and manage overlap control for all of our household surveys. The HSF lists PSUs with attributes determined by data from the census. PSUs are then assigned to standard strata based on these attributes. For this survey, we selected a sample of 1,600 PSUs.

The second stage of selection involves retrieving 2013 Census records from within the selected PSUs, and drawing the final sample from these. We eliminate the following from the census data before selecting the final sample:

  • individuals in non-private dwellings
  • individuals for whom age cannot be derived
  • other invalid records.

The third stage of selection involves randomly subsampling one person from households where more than one person was originally selected. So, if three people were selected after the second stage of selection, we discard two of them at random. This ensures that we interview only one person from each private household that we select for the survey.

We selected a sample of 23,000 people for the HDS, out of which 14,900 were adults and 8,100 were children.

Sample design for DSRF

The sampling frame for the DSRF is provided by the Ministry of Health and is a list of the number of beds in all residential facilities.

The sample for the DSRF was selected in two stages:

  1. selection of residential facilities
  2. selection of residents within the selected facilities.

At the first stage, we used three strata (rest homes, hospitals, and residential facilities) to sample facilities. We used proportional sampling to allocate residents to strata. See table below for information about the strata used for the DSRF.

Strata  Type of residential care facility included
1. Rest home  Rest home: standard-level care
   Rest home: dementia
 2. Hospitals  Hospital: continuing care (age and geriatric)
   Hospital: specialised care (psycho-geriatric)
 3. Disability facilities  Residential: intellectual disability
   Residential: physical disability
   Residential: sensory disability
   Residential: psychiatric disability
   Residential: multi-disability

At the second stage, we selected residents within facilities by probability proportional to size (PPS) sampling. We selected five residents per facility in the strata ‘rest homes’ and ‘hospitals’, and three residents from the strata ‘disability facilities’, since most of these facilities have fewer than 10 residents.

The interviewer selected the residents from each facility from a list of eligible residents provided by the facility. If a facility offered multiple types of care (rest home, hospital, and/or other residential disability care) we separated it into multiple facilities. It was possible for a facility to be selected twice in the survey.

The final selected sample for the DSRF was 864 individuals from 177 residential facilities.

Reliability of survey estimates

The estimates in this publication are based on information obtained from a sample of people, and are therefore subject to sampling variability. That is, the estimates may differ from results that would have been produced if all people were included in the survey.

Two types of error are possible in estimates based on a sample survey: non-sampling error and sampling error.

Non-sampling errors are all errors that are not quantifiable. They include unintentional mistakes by respondents, variation in the respondent's and interviewer's interpretations of the questions asked, and errors in recording and coding data. We try to minimise the impact of these errors by applying best survey practices and monitoring known indicators (eg non-response).

Sampling error can be measured, and quantifies the variability that occurs by chance because a sample rather than an entire population is surveyed. In the 2013 Disability Survey, sampling errors were estimated using a jack-knife method. This method is based on the variation between estimates, and involves taking 100 mutually exclusive subsamples from the whole sample. Sampling errors are quoted at the 95 percent confidence level. For example, if the estimated total number of people is 315,000 and the estimate is subject to a sampling error of plus or minus 7,250 or 2.3 percent (measured at the 95 percent confidence level), that shows there is a 95 percent chance that the true total number of people lies between 322,250 and 307,750.

Relative sampling errors (RSE) show the sample error as a percentage of the estimate. These figures will not give a precise measure of the sample error for a particular estimate, but will indicate its magnitude. Smaller estimates, such as the number of disabled Pacific peoples who are unemployed, are subject to larger RSEs than larger estimates. Very small estimates are subject to such high sample errors (relative to the estimate) as to detract seriously from their value for most reasonable uses.

Presentation of information

Weights

The survey has weights attached to allow the survey sample to be used to describe the whole population resident in New Zealand. Weights for this survey are at the person level only.

Confidentiality and suppression

Estimates with very few contributors are deemed a risk to respondents’ confidentiality. Estimates based on an estimated population of less than 1,000 are suppressed. This is indicated in tables by an ‘S’.

Estimates with high relative sample errors (RSE) are suspect in quality. Therefore all estimates with an RSE of 50 percent or greater are suppressed. Estimates with an RSE of 30 percent to 49.9 percent should be viewed with caution (indicated in tables by an asterisk *), and an error of 50 percent or greater will be indicated by an ‘S’.

Rounding and percentages

Estimated counts in this release are rounded to the nearest 1,000 people.

All percentages shown in the text and tables are calculated from unrounded weighted data and then rounded to whole figures. If one of the figures used to calculate a percentage has been suppressed, the percentage will also be suppressed.

Unless otherwise stated, calculation of percentages in this report excludes responses we can’t classify (eg ‘don’t know’ and ‘refused’).

More information

Customised data requests

Phone our Information Centre on 0508 525 525 toll-free, or email info@stats.govt.nz, to discuss options for getting customised data that suits your needs. There may be a charge for a customised request. 

See Disabilities for more information. 

Liability

While all care and diligence has been used in processing, analysing, and extracting data and information in this publication, Statistics NZ gives no warranty it is error-free and will not be liable for any loss or damage suffered by the use directly, or indirectly, of the information in this publication.

Timing

Our information releases are delivered electronically by third parties. Delivery may be delayed by circumstances outside our control. Statistics NZ does not accept responsibility for any such delay.

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