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Appendices

Appendix 1: Predictive factors at different ages

The table below outlines the number of models in which a predictor was selected for inclusion in the modelling at each age.[21] Each predictor could be used in up to eight models (up to age 20), one for each of the four outcomes for both males and females. A zero in the table indicates that the factor was not included in any of the regression models at that age, while a missing value indicates that the factor was not available for inclusion, generally because that type of information was not available at that age.

Appendix 1 Table 1: Predictive factors and number of models by age
Risk factor Age
15 16 17 18 19 20 21* 22 *†

Socio-demographic and location characteristics

Ethnicity 8 8 8 8 8 8 6 4
Territorial authority 6 5 5 4 4 4 1 0
New Zealand Deprivation Index (NZDep) decile 7 7 6 5 3 3 1 0
Currently overseas 0 1 0 1 3 3 1 2

Childhood risk factors

Notified to CYF care and protection as a child 8 8 8 8 8 8 5 3
CYF care and protection maltreatment finding 2 2 1 1 2 1 2 1
Placed in care of CYF care and protection 6 6 4 3 0 2 0 0
Referred to youth justice 7 8 7 6 6 6 4 4
Placed in care by youth justice 2 2 2 2 1 1 1 1
Maternal caregiver education/benefit status 8 8 8 8 8 6 5 2
Caregiver with community sentence 7 8 7 7 4 5 2 1
Caregiver with custodial history 4 1 0 0 1 1 1 0
Duration on a benefit as a child 5 3 3 2 3 2 0 0
Main type of benefit as a child 3 3 3 3 1 2 0 1

Schooling characteristics

Enrolled at school 0 0 7 5 4 2 2 0
Type of school (private, state etc.) 0 0 0 0 0 0 0 0
Currently in special school 4 4 1 0 0 1 0 0
Ever received special education services 5 5 5 5 5 4 3 3
Ever stood down from school 8 7 7 7 6 6 3 0
Ever suspended from school 7 7 4 4 2 4 1 1
Ever truant from school 2 6 2 2 1 2 1 0
Last school decile 6 6 6 4 3 3 1 0
Last school was correspondence 1 1 0 0 1 1 0 0
Last school was private 1 2 1 3 0 1 1 0
Achieved level 1 NCEA or equivalent 0 8 3 2 0 0 0 0
Achieved level 2 NCEA or equivalent 0 2 2 5 4 4 1 0
Achieved level 3 NCEA or equivalent 0 0 1 3 3 3 1 1

Tertiary education

Enrolled for 1 year in tertiary education 1 3 1 3 0
Enrolled for 2 years in tertiary education 1 1 3 2 0
Enrolled for 3 years in tertiary education 2 0 3 1
Latest tertiary enrolment level 3 4 4 3 3 0
Highest school or tertiary level completed 1 0 5 4 3 3 2 0
Highest tertiary enrolment level 0 3 6 5 5 2

Employment and welfare characteristics

Duration not in employment, education or training (NEET) last year 8 2 3 2 2 1
Duration NEET since 16 0 8 8 6 4 1
Duration NEET since 18 0 2 2 1
Ever on a benefit as an adult 3 5 1 4 1 0
Main benefit type since age 18 1 5 4 2 2
Main benefit type last year 5 4 4 3 6 3
Duration on a benefit since age 18 0 2 2 4 4
Duration on a benefit last year 0 0 3 2 4 3
On a benefit for 2 years as adult 0 1 0 2 1 0
Any earnings in last 2 years (wages and salaries and self-employment) 1 1 2 2 0 3 1 0
Any earnings in last year 4 4 1 0 2 0 0 1
Average earnings in last 2 years 1 0 2 3 3 3 2 0
Total earnings in last year 1 5 3 4 5 4 3 1

Corrections contact

Served community sentence 2 2 1 1 0
Served custodial sentence 0 0 1 0 0
Served some sort of corrections sentence 5 7 6 5 3
Use of mental health services
Used alcohol or drug addiction services 0 0 0 1 0 1 0 0
Used any mental health services 0 0 0 0 0 0 0 0
Used other mental health services 0 0 0 5 4 4 1 2
Indicator of any mental health illness 1 1 1 1 2 1 1 0
Indicator of other mental health illness 7 7 7 7 5 7 2 0
Indicator of substance abuse 2 3 2 2 2 2 1 1

Early parenting and offspring childhood risk factors

Parent 0 0 1 1 1 1 1 0
Early parent (before age 19) 0 0 0 0 0 0 0 0
Had own child in placement or with maltreatment finding 0 0 0 0 0 0 0
Had own child in Police/family violence notification 2 1 1 3 2 1 0
Had own child placed in CYF care 1 1 1 1 1 1 0
Had own child with maltreatment finding 2 1 1 1 2 1 1
Own child referred to youth justice
Number of models run* 8 8 8 8 8 8 6 4
Average factors included per model 15.6 18 18.4 21 20.5 20.5 18 12.8
Potential factors 42 46 54 61 63 63 63 63

* At age 21, only three outcomes were modelled, and factors could be included in only six models (rather than eight). At age 22, only two outcomes were modelled, and factors could be included in only four models.

† The 22-year-old models were also applied to the population at ages 23 to 25.

Notes

  • [21]As discussed in the body of the paper, only those predictors that were statistically significant based on a forward selection approach were included in each model.
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