The Treasury

Global Navigation

Personal tools

5.3 Target population overlap and coverage

Despite the attempt to identify target populations that not only predict risk well and are identifiable through a few simple criteria but also are mutually exclusive from each other, in practice, these objectives tend to counteract each other, and a trade-off is necessary to reach a balance across the objectives. Figures 3 and 4 below illustrate the degree of overlap between each target population and the other target populations identified in the same age range using Venn diagrams as well as the overlap between the target populations and the at-risk population (those with extreme risk of one or more poor outcomes). These figures relate to the December 2013 population, while overlaps and coverage of the 1990/91 birth cohort population are illustrated in Appendix 6.

The Venn diagrams were designed to be area proportionate such that the area covered by each part of the diagram relates to the size of the populations that meet the relevant criteria. This was accomplished using ellipses instead of circles to represent the different populations.[19] Whilst each Venn diagram is designed to be area proportionate within itself, the diagrams are only broadly comparable with each other, and caution should be taken inferring areas as being equivalent across different diagrams.

Figure 3 shows the various 15 to 19-year-old target populations. Between them, the target populations cover 72% of the total at-risk population, while around 36% of people classified as being in at least one target population do not meet the definition of being at risk. Despite this latter percentage being higher than we might like, these young people may have higher risk than the average person in the not-at-risk population. Between 43% and 60% of the target populations also fall in at least one other target population. The former, with the lowest overlap, is the 'Teenagers with health, disability issues or special needs' group, while the latter, with the highest overlap, is the 'Teenage girls supported by benefits' group.

Figure 4 shows the various 20 to 24-year-old target populations. These target populations cover 82% of the total at-risk population, while 25% of people classified as being in at least one target population do not meet the definition of being at risk. Both of these are an improvement on the younger target populations, reflecting the improving ease of prediction with age. Overlap between target populations is also considerably lower at the older ages, ranging from 7% to 41% (for the 'Long-term disability beneficiaries' and 'Jobseekers in poor health with CYF history' groups respectively).

Table 21: Target population descriptions, criteria, size and estimated risk
Target population descriptor Criteria Number (2013 popn) Extreme risk of one or more poor outcomes High risk across multiple poor outcomes

Age 15 to 19

       
Teenage boys with Youth Justice or Corrections history
  • Boys aged 18-19 with Corrections history
  • OR Boys aged 15-17 with Youth Justice contact
  • OR Boys aged 15-17 caregiver with custodial history
12,801 68% 76%
Teenagers with health, disability issues or special needs
  • Aged 17-19 and on Supported Living Payment Benefit
  • OR Aged 15-19 and used special education services
  • OR Aged 15-19 and attended a special school
5,769 87% 46%
Teenage girls supported by benefits
  • Girls aged 15-19 with no qualifications and significant duration on benefit as adult
  • OR Young mothers aged 15-19 on Sole Parent Support Benefit
4,212 74% 79%
Mental health service users with stand-down or CYF history

Aged 15-17, used mental health services AND:

  • Contact with Child, Youth & Family (CYF) Care and Protection
  • OR History of stand-downs from school
10,926 82% 81%
Experienced significant childhood disadvantage

Aged 15-19 AND:

  • History of placement in care by Child, Youth & Family
  • OR Notified to CYF with a caregiver with a Corrections history AND supported by benefit for more than 75% of childhood
16,128 71% 83%
Not in a target population None of the above criteria 253,020 5% 7%

Age 20 to 24

       
Young offenders with custodial sentence 20-24 year olds with a custodial sentence 8,208 86% 88%
Young offenders with community sentence and CYF history

20-24 year olds with a community sentence (but no custodial sentence) AND:

  • A Youth Justice referral
  • OR Notified to CYF
9,543 72% 78%
Jobseekers in poor health with CYF history

Received Jobseeker Health Condition, Injury or Disability Benefit for 95% of last year AND:

  • Received a Corrections sentence
  • OR referred to Youth Justice
  • OR referred to Child Youth & Family
2,316 77% 98%
Sole parents not in fulltime employment with CYF history

Received Sole Parent Support benefit for > 95% of last year AND:

  • Received a Corrections sentence
  • OR referred to Youth Justice
  • OR referred to Child, Youth & Family
6,117 72% 96%
Long-term disability beneficiaries 20-24 year olds who recieved supported living payment for > 85% of last year 4,521 94% 36%
Not in a target population None of the above criteria 264,111 2% 8%

Figure 3: Target population overlaps December 2013 population, ages 15 to 19

Figure 3: Target population overlaps December 2013 population, ages 15 to 19.

Figure 4: Target population overlaps December 2013 population, ages 20 to 24

Figure 4: Target population overlaps December 2013 population, ages 20 to 24.

 

Notes

  • [19]A software package called eulerAPE was used to represent the areas of overlap in Venn diagram form. See: Luana Micallef and Peter Rodgers (2014). eulerAPE: Drawing Area-proportional 3-Venn Diagrams Using Ellipses. http://www.eulerdiagrams.org/eulerAPE
Page top