The role of judgment in turning evidence into guidance


I came across a sentence about risk assessment in another class that I am taking that struck me as particularly relevant to knowledge translation (KT). In the textbook chapter on Risk Assessment, there is a section titled “Is Risk Assessment a Science?”. It reads:

Although it relies heavily on science-based information, risk assessment does not generate new empirical evidence on health effects in the way that toxicology and epidemiology do. Instead risk assessment can be viewed as a synthesis of existing scientific information, often aimed at addressing specific regulatory or policy issues. This is why risk assessment has been referred to as a mixture of “science and judgment.” (Frumkin, 2010, p. 1038).

I think this quote illustrates well the tension that sometimes (often?) exists between scientists and decision-makers. Scientists work in a systematic and rigorous way to obtain empirical evidence, but where does that leave us? What can be done with this evidence? It is the role of the environmental health risk assessor to apply “a quantitative framework for evaluating and combining evidence from toxicology, epidemiology, and to other disciplines with the goal of providing a basis for decision-making” (Frumkin, 2010, p. 1038). That is, to turn the empirical evidence the scientists have provided into guidance.

While I may be reading into it, I find the quote reflects certain uneasiness around the fact that risk assessment involves judgment and therefore strays away from “science”. And it is easy to see why the presence of judgment in risk assessment could make people uneasy.  Obviously, when faced with a hazard that is potentially very harmful to human health, one should be wary about who is making the call on how safe it is for people to be exposed to it; what are the values of the risk assessor and whose interests might they be taking into consideration is the assessment?

Still one cannot very well just eliminate judgment. As we saw last week in our class discussion of different types of reviews, each method required the reviewer to make judgments – how will the research question be framed, what are the inclusion and exclusion criteria, what counts as evidence. In his article on indifference towards research-based evidence, Lewis (2007) points out some of the ways evidence and judgment interact to complicate evidence-based decision making. In particular two propositions struck me as particularly relevant to risk assessment: “Proposition 5: Everyday life is normative, but there is no science to human values” and “Proposition 6: Evidence often makes decision-making more difficult, not less”. With these two propositions, Lewis points out that judgments involve not only technical, but also social and philosophical considerations  – who’s needs are most important, do we think of the collective or of the individual.

The process of turning evidence into guidance is clearly not always straightforward. Yet it is necessary to ensure that research does make its way to policies that can improve people’s lives. So given that judgment is inevitable in taking evidence and turning it into guidance for decision-makers, what is the best way to make those whose role it is to evaluate and combine evidence the best possible judges?


Frumkin, H. (2010). Environmental Health: From Global to Local (2nd Ed). John Wiley & Sons.

Lewis, S. (2007). Towards a general theory of indifference to research-based evidence. Journal of Health Services Research & Policy.



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