Paper explores making public policy with limited information
How might policymakers make reasonable decisions when they have limited information?
That's the question Northwestern University's Charles F. Manski explores in his new paper, "Vaccination With Partial Knowledge of External Effectiveness." The paper is published online by the Proceedings of the National Academy of Sciences (PNAS) at http://www.pnas.org/content/early/2010/02/05/0915009107.full.pdf+html.
"Let's say you're a public health official from the Centers for Disease Control, and you don't really know how much disease is going to be averted by vaccinating different fractions of the population," said Manski, the Board of Trustees Professor in Economics in the Weinberg College of Arts and Sciences. "Then how should you choose a policy? That's really what the paper tries to address."
In his paper, Manski sets up the following scenario: "You can look back over the last year and say we vaccinated 30 percent of the population, and this is what happened. But the question you want to answer is whether 30 percent is a good fraction to vaccinate [from a public health perspective] because you don't observe what would have happened if last year you had vaccinated 40 percent, 20 percent or 80 percent."
In this case, Manski, whose research spans econometrics, judgment and decision, and the analysis of social policy, said there are at least two sources of partial knowledge. First, the policymaker may only partially know how effective the vaccination will be in generating an immune response. Second, the policymaker may only partially know how effective the vaccination will be in preventing transmission of the disease to members of the public.