1. Understanding Inertia
Inherent Limitations on Evaluating “Upstream” Prevention Interventions

2. Intervention Strategies
“Upstream” Interventions
School and community based prevention
Disrupting Supply
“Downstream” Interventions
Treatment
Incarceration of Users
Enforcement/Treatment Partnerships

3. Understanding Inertia
Empirical illustration using household survey data
Structural explanation with a model of illicit drug use
Mathematical representation of system inertia

4. Empirical Illustration
Source SAMDHA 2006

5. One Year Interruption of Initiation

6. One Year Interruption of Initiation

7. Permanent 33% Drop

8. Permanent 33% Drop

9. Two-Stage Model

10. Two-Stage Model

11. Two-Stage Model

12. Mathematical Representation
f(t) probability that an individual manifests outcome of interest in year t
I(t) Initiation in year y
X(t) aggregate level of outcome at time t

13. Convolution Integral One year interruption of initiation with
f(t)=1 for
T = 0.5,
T = 1,
T = 2,
T = 10,
years.

14. Conclusions
For upstream interventions evaluated with downstream indicators…

15. Conclusions
For upstream interventions evaluated with downstream indicators…
…No news is really no news.

16. Thanks!