A key issue in the design of interventions is whether they should be universally available, available to a targeted group identified as at risk of negative outcomes or limited to those identified as already having demonstrated a negative outcome. Examples of universal interventions include legislation such as family law and the provision of services, such as child immunisation. Examples of targeted interventions include the provision of specific services to an identified group, such as counselling for teenagers with mental health disorders.
Targeting interventions can involve Type I and Type II errors, providing services to those who do not need them or failing to provide services to those who do need them. This suggests that the level of risk should be matched to the degree of targeting, so that universal interventions are provided where risk is low and a target population hard to identify, whereas more targeted approaches are appropriate when greater risks become apparent and at-risk individuals are easier and cheaper to identify (Andrews and Bonta 1998). The overall portfolio is therefore likely to include not only a mix of universal, targeted and indicated intervention, but also interventions that are designed for early and later stages.
Evidence that outcomes of children are influenced by the characteristics and circumstances of their parents and that circumstances and behaviours at different stages of development help in the prediction of subsequent outcomes suggests that early interventions targeted on children identified as most at risk can reach and help most children who would otherwise have difficulties later in life.
However, practical programme portfolio design is more complex. While intensive, risk-factor targeted, early interventions can reduce the incidence of later problems and improving long-term outcomes, they are likely to reach few of those who later have severe problems. At the same time, targeted interventions will be applied to many children who will not have problems in later life. More broadly-focused interventions are likely to be an efficient addition to the portfolio of services available, particularly those which are grafted onto universal programmes. Later responses to problems as they emerge in later childhood and adolescence are likely to be needed.
For example, a study using data from the CHDS showed that a sub-group of individuals at high risk of problem behaviour at 15 were significantly more likely than the remainder of the sample to have experienced disadvantage throughout their earlier childhood (Fergusson, Horwood and Lynskey 1994b, Fergusson, Horwood and Lynskey 1994a). At the same time, only 40% of the most problematic teenagers had exhibited the highest level of risk in earlier childhood (Table 7).
|Earlier childhood disadvantage score||Percentage of sample||Number of multiple problem teenagers||Percentage of multiple problem teenagers||Rate (%) of multiple problem behaviour|
|0 – 6||54.5||1||3.7||0.2|
|7 – 12||29.8||7||25.9||2.5|
|13 – 18||10.3||8||29.6||8.3|
Source: Fergusson (1994a)
Indeed, in order to reach 70% of the eventual multiple-problem group of 15-year olds, at least 16% of all children would have needed to be targeted for special attention. On the other hand, even a very tightly targeted strategy, focusing on the 5.4% of children with the highest scores, would involve intervening with a large proportion of children (80%) who do not need the intervention.
A more optimistic picture of the scope for early intervention with high-risk children (ie, up to age 14 years) to prevent later problem behaviour comes from the crime prevention field, where the small group of children and young people who are at high risk of becoming serious adult offenders can be identified with increasing certainty from birth to the beginning of their adult offending career (Moffitt and Caspi 2001). As a result, preventive policies have the potential to bring about larger reductions in crime and imprisonment rates than any other available strategy (Department of Corrections 2001). The focus on serious offending rather than the broader category of problem behaviour seems to make early targeting of at-risk individuals more efficient.
Table 8 summarises the estimated costs and benefits of a range of preventive interventions designed to interrupt the criminal trajectory of children and young people at four different points in the life cycle at which successful preventive interventions have been demonstrated in the literature (Department of Corrections 2001). Later interventions (after age 14 years) cost more and are less successful.
|Intervention point||Description of service||Estimated cost per case||Estimated benefit/cost ratio|
|Before birth||Effective family planning advice to very high-risk young women in the youth justice, child protection and adult justice systems||$500||50:1|
|At birth||Further expansion of the Family Start programme. Identify high-risk births and support mothers and families||$3,000||25:1|
|At entry to primary school||Identify behaviour disorder and provide a behaviour change programme including support for family and school||$5,000||51:1|
|Early youth offending`||Risk assess persistent early offenders (age 10-14 years). Provide intensive services directed to criminogenic needs for selected cases.||$10,000||25:1|
Note: The benefit-cost ratios given are an estimate of the crime prevention return per dollar spent on the intervention taking into account the costs to taxpayers and to victims of crime.
Source: Department of Corrections (2001)
Interventions are typically provided on a universal basis to prevent the onset of poor outcomes when it is difficult and costly to identify the at-risk population. They are provided on a targeted basis to prevent or ameliorate negative outcomes when it is possible to identify a population at-risk and on an indicated basis to prevent the worst effects of negative outcomes where high risk individuals can be identified.
Universal services can play a key role in facilitating the development of skills and abilities that mitigate the risk of negative outcomes. For example, empirical evidence suggests that education is a key protective factor. The longer children stay in education, the less likely they are to commit a crime, be unemployed, or have poor health outcomes. Some universal services can support the provision of more targeted services by identifying those at risk. Targeted services can also be nested in universal services, enabling them to be delivered in a more cost-effective manner. Examples include the provision of specialist education services within mainstream schooling. Other advantages from universal provision of services include inclusivity and lack of stigma for users (Offord, Kraemer, Kazdin, Jensen, Harrington and Gardner 1999).
There are disadvantages of universal provision of programmes and services. These include the high cost of provision, particularly for demand-driven services; potential inefficiencies and low cost-effectiveness, as services may be provided to those who do not need them; potential displacement of private investment in such services by individuals, families and communities; potential inequities, as they may accrue additional benefits to those who are already advantaged or direct resources away from those who are most in need. In addition, the benefits of universal programmes are difficult to evaluate because they are provided equally to everyone.
Most targeted services are aimed at developing and enhancing protective factors associated with positive outcomes, or preventing the emergence of behaviours or conditions associated with negative outcomes. The key benefit of targeted interventions is that they are focused on preventing the emergence of a negative outcome, thereby reducing the potential future social and economic cost that might be associated with that outcome. However, they are susceptible to Type I and Type II errors. Narrow targeting will increase the probability that some people who will have negative outcomes will not receive services, while loose targeting may mean higher costs and more deadweight losses.
To be effective, targeted programmes need to be underpinned by a clear understanding of the risk factors that are implicated in particular negative outcomes and the causal pathways that exist between particular factors and outcomes, so that they tackle the right factors at the right time. Targeted interventions also depend on reliable and cost-effective screening mechanisms to identify those most at risk.
Targeted programmes may be provided where problems have already become apparent. These interventions usually aim to improve outcomes by treating the problem and preventing or minimising its recurrence. They may also focus on developing factors (such as the development of employment skills amongst young offenders) to protect against further negative outcomes. Well-designed services targeted on the basis of indicated risk are likely to be cost-effective because there is a greater probability that they are focused on the right population. On the other hand, they may be more costly and more likely to fail because they are trying to change established situations or behaviours.
Universal programmes typically focus on improving the well-being of the least well-off by raising the mean of the population distribution while targeted interventions tend to focus on directly raising the outcomes of those likely to do least well. Sometimes the focus of policy will be to raise the absolute level of performance of those at the bottom of the population distribution of outcomes rather than a concern with what happens to the mean.