Appendix A

Using data from the IDI and What About Me? survey

The IDI

The IDI is a large research database that holds deidentified data about people and households. This includes data that government agencies and NGOs
Non-government organisationsView the full glossary use to manage the services they provide to the public (administrative data) and data from surveys run by Stats NZ.

We used IDI data because:

  • it links de-identified data from different sources about individuals and households so we can see the range of services that individuals and whānau
    Whānau refers to people who are biologically linked or share whakapapa. For the Monitor’s monitoring purposes, whānau includes parents, whānau members living with tamariki at the point they have come into care View the full glossary     receive
  • it means we can follow a range of outcomes for tamariki
    Children (plural) aged 0-13 yearsView the full glossary     and rangatahi
    Young person aged 14 – 21 years of ageView the full glossary     both while they are in the oranga tamariki system and later after they have left the system and move into adulthood.

Stats NZ has strict criteria for using the IDI so people’s information is protected. You can find more detail about how Stats NZ keeps data safe on its website.182

Stats NZ’s disclaimers about using the IDI

We are required to make the following disclaimers about data from the IDI.

Access to the data used in this study was provided by Stats NZ under conditions designed to give effect to the security and confidentiality provisions of the Data and Statistics Act 2022. The results presented in this study are the work of the author, not Stats NZ or individual data suppliers.

These results are not official statistics. They have been created for research purposes from the IDI, which is carefully managed by Stats NZ. For more information about the IDI please visit stats.govt.nz/integrated-data/

The results are based in part on tax data supplied by Inland Revenue to Stats NZ under the Tax Administration Act 1994 for statistical purposes. Any discussion of data limitations or weaknesses is in the context of using the IDI for statistical purposes and is not related to the data’s ability to support Inland Revenue’s core operational requirements.

Technical definitions of IDI indicators

Our analysis considered people who were living in Aotearoa
New ZealandView the full glossary during 2023.

We grouped this population based on their age at the end of 2023:

  • Tamariki and rangatahi aged 0–17 during 2023.
  • Young adults aged 18–25 during 2023.

We also grouped the population by level of involvement with Oranga Tamariki. We used these age groupings because:

  • tamariki and rangatahi aged 0–17 may be currently involved in the oranga tamariki system
  • young adults aged 18–25 who were in care or custody may be eligible for TSS during the year.183

We show the framework for classifying interaction with the oranga tamariki system below.

Grouping the population by level of involvement in the oranga tamariki system
Aged 0–17 No Oranga Tamariki involvement Care or custody
Aged 18–25 No Oranga Tamariki involvement Care or custody: Ineligible for TSS Care or custody: Eligible for TSS

Defining disability

For this work, a person was defined as experiencing a disability if they did any of these things:

  • Responded to questions184 in Census 2023, Census 2018 or a social survey as experiencing disability.
  • Received a Disability Allowance or was a child whose parent received a Child Disability Allowance on their behalf.
  • Received an Invalid’s Benefit or Supporting Living Payment (excluding carers).
  • Received Ongoing Resourcing Scheme support or School High Health Needs funding.
  • Was a Whaikaha – Ministry of Disabled People client.

Definitions of measures

The table below contains definitions for the measures we used in this report. You can find full technical definitions for the measures and the software code we used to produce the measures on our repository site.185

Measures marked with an asterisk * used a code module. The code modules initiative is an effort backed by government agencies and non-government users of the IDI to make the integrated data assets easier to use and understandable for everyone, including non-technical people. 186 Code modules contain high-quality code and documentation for foundational measures needed by researchers.

Health measures
Measure Definition
Primary Healthcare Organisation (PHO) enrolment For tamariki
Children (plural) aged 0-13 yearsView the full glossary and rangatahi
Young person aged 14 – 21 years of ageView the full glossary aged 0–17 or for young adults aged 18–25.
An individual is enrolled with a PHO within the relevant year. A PHO manages a group of contracted general medical (GP/family doctor) practices. If an individual chooses to register as a patient of a medical practice, they will be enrolled in the corresponding PHO and receive subsidised healthcare.
GP visit For tamariki and rangatahi aged 0–17 or for young adults aged 18–25.
An individual has consulted a GP at their registered practice at least once within the relevant year. This measure is limited to those enrolled with a PHO as it does not include consultations with GPs made as a casual patient.
Mental health and addiction service use For tamariki and rangatahi aged 0–17 or for young adults aged 18–25.
An individual accessed secondary public inpatient or community mental health and addiction services at least once within the relevant year. Note this measure does not include primary healthcare settings such as GP consults, which may also be used to address mental health or addiction issues.
Self-harm hospitalisation For tamariki and rangatahi aged 10–17 or for young adults aged 18–25.
An individual was hospitalised at least once during the year with a diagnosis that indicated intentional self-harm or self-injury with undetermined intention. 
Education measures
Measure Definition
School attendance*

For tamariki and rangatahi aged 0–17.
Grouped into primary/intermediate and secondary school attendance. For students enrolled at state or state-integrated schools, their attendance in term 1 within the relevant year. For each student, attendance is recorded for each half-day as attending, justified absence or unjustified absence. The half-days a student was recorded as attending were divided by the total of half-days and ranked into bands of:

  • regular attendance (present for 90% or more of the term)
  • irregular absence (present for 80% or more but less than 90% of the term)
  • moderate absence (present for 70% or more but less than 80% of the term)
  • chronic absence (present for less than 70% of the term).
Social support measures
Measure Definition
Supported by main benefit* For young adults aged 18–25.
An individual received a main benefit for the whole year, for example the individual has been continuously receiving a main benefit for a spell of 365 days or more during the year (counting only days within the year). Main benefits include Sole Parent Support, Jobseeker Support, Supported Living Payment, Young Parent Payment and Youth Payment.
Emergency housing spell For young adults aged 18–25.
An individual was the principal applicant for an Emergency Housing Special Needs Grant at least once within the relevant year.
Other measures
Measure Definition
Driver licence* For young adults aged 18–25.
An individual held a current New Zealand restricted licence or class 1 full licence (car licence) or class 6 full licence (motorcycle licence) at the end of the relevant year. This excludes licences that are not current, for example, licences that are expired or suspended, and excludes people who only hold overseas licences.
In employment For young adults aged 18–25.
An individual received income from wages, salary or paid parental leave during a month. This is presented as the average across all months in the calendar year for the proportion employed within each group. This was done for simplicity, as the figure for each group was relatively constant throughout the year.

What About Me? survey

What About Me? was a nationwide survey of rangatahi
Young person aged 14 – 21 years of ageView the full glossary aged 13–18. It was done on behalf of the Ministry of Social Development in 2021.

Just under 8,000 rangatahi responded to questions about their health, wellbeing, whānau
Whānau refers to people who are biologically linked or share whakapapa. For the Monitor’s monitoring purposes, whānau includes parents, whānau members living with tamariki at the point they have come into care View the full glossary and community. This included just over 7,000 rangatahi in years 9–13 at school and a further 500 rangatahi of the same age in the community.

We were only able to access the dataset from Stats NZ for those rangatahi who completed the survey in schools. This means the measures do not represent rangatahi who do not regularly go to school. This is unfortunate because IDI measures show that some groups of rangatahi in the oranga tamariki system are less likely go to school regularly and are therefore less likely to have their views represented in the school sample.

The survey included questions about ethnicity and involvement with Oranga Tamariki. This enabled us to understand:

  • how tamariki
    Children (plural) aged 0-13 yearsView the full glossary     and rangatahi Māori or non-Māori who had been involved with Oranga Tamariki187 felt about many aspects of their life
  • how this compared to those who had never been involved with Oranga Tamariki.188

Subjective wellbeing measures are particularly important because most administrative data comes from people’s interactions with government agencies and services – it doesn’t tell us anything about people’s views on their own lives.

The questionnaires for the What About Me? and Youth2000 surveys were merged to form the Youth Health and Wellbeing Survey.189 The Ministry of Social Development conducted the 2025 round of this survey in early 2025 and intends to repeat it every three years. We expect results for the Youth Health and Wellbeing Survey 2025 to be available in 2026.

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Footnotes

182 stats.govt.nz/integrated-data/how-we-keep-integrated-data-safe/
183 For more details about the Transition Support Service, see orangatamariki.govt.nz/children-in-our-care/transition-support-service
184 For more details about the Transition Support Service, see orangatamariki.govt.nz/children-in-our-care/transition-support-service
185 github.com/nz-social-investment-agency/Children-interacting-with-the-OT-system
186 For more information about the code modules initiative, see www.stats.govt.nz/integrated-data/code-modules-initiative
187 The group of What About Me? survey respondents involved with Oranga Tamariki included any tamariki
Children (plural) aged 0-13 yearsView the full glossary and rangatahi
Young person aged 14 – 21 years of ageView the full glossary who answered yes to ‘Have you or anyone in your family every been involved with Child, Youth and Family Services (CYFS) or Oranga Tamariki?’ This includes those who have had a social worker visit them or their family, had an FGC or been in care.
188 The survey sample included responses from 6,059 young people with no involvement with Oranga Tamariki and 1,150 young people who were involved with Oranga Tamariki.
189 For more information about the Youth Health and Wellbeing survey, see msd.govt.nz/about-msd-and-our-work/publications-resources/consultations/youth-health-and-wellbeing-survey-results/index.html