modelling approaches to policy issues in public health dr philippe giabbanelli public health...
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Modelling approaches to policy issues in public health
Dr Philippe GiabbanelliPublic Health Modelling group
14 November 2014
What is modelling?
Modelling is articulating a set of hypotheses about a phenomenon.
All people model. But most run implicit, rather than explicit models.
What is modelling?
Implicit models Explicit modelsvs
• Hide underlying hypotheses • Show testable hypotheses
• Don’t test internal consistency
• Unknown relation to data
• Check for consistency
• Incorporate data
What is modelling?
There are different ways to do modelling.
Mathematical model Statistical model Computational model
None is systematically better. They address different needs.
Conceptual model
When do computational models help?
Computational models have a strong track-record in supporting decision making in complex situations.
information is never complete, comes in incrementally – but there is constant pressure to arrive at conclusions
When do computational models help?
“The high cost to eradicate poliomyelitis in 4 endemic areas has led some to suggest switching from eradication to a policy of control.”
Modelling
Wavering commitment leads to a failure to eradicate, greater cumulative costs, and a much larger number of cases.
Case#1: Eradicating, or controlling?
Closing schools during the 2009 H1N1 influenza epidemic would have:↓ transmission (hence deaths and health care costs)
↑ costs of childcare needs↓ productivity of school employees
Modelling
Closing schools could have resulted in substantial costs to society.
When do computational models help?
Case#2: Closing schools or not?
When do computational models help?
When do computational models help?
• interdisciplinary • rich and accessible data
• usable model • scenarios informed by policymakers
• method selected based on the problem
Modelling food behaviours
How would food behaviours respond if we started changing prices?
Modelling food behaviours
Tax
Published in the American Journal of
Public Health
Modelling food behaviours
Previous computational models assume that:
the relationship between the food environment “foodscape”) and food consumption can be captured by looking at the
foodscape around the home or work environment
Proximity hypothesis
…but people navigate a multiplicity of environments
and it depends on food preferences, socio-demographics, etc.
Modelling food behaviours
Agent-based model
Portfolio of policy interventions
Maximum density of takeaways minimum distance of takeaways from schools
preference for healthy foods
Indicators
Utilization per type of food outlet F&V intake Obesity
Conclusion
For more information about the Public Health Modelling group, visit:http://www.cedar.iph.cam.ac.uk/research/modelling/
Modelling can support decision making in complex situations but it has to follow a transparent and interdisciplinary process using good
quality data to investigate credible scenarios.