Statistics New Zealand provides many free sources of statistical data.
figureNZ - a trust which cumulates NZ statistics from any sources
Pātaka Raraunga - Data for and about Māori
Pacific Data Fale o Aotearoa - Data for and about Pacific peoples
Child and Youth Health Statistics
Child and Youth Prosecution Tables (Statistics New Zealand)
Dunedin Multidisciplinary Health & Development Study - well known longitudinal study which follows the development and wellbeing of participants from birth.
Statistics New Zealand - crime and justice statistics
New Zealand Police statistics - provides access to policedata.nz which creates reports on a range of topics
Ministry of Justice: Research and Data includes:
New Zealand Crime and Safety Survey
New Zealand Crime and Victims Survey
Data tables on specific offence types and population groups
New Zealand Family Violence Clearinghouse - family violence statistics
Family violence statistics - New Zealand Family Violence Clearinghouse
Child, Youth and Family - key statistics
Children and Youth affected by Family Violence - New Zealand Family Violence Clearinghouse