The November seminar of the Stats Society will take place at the Clayton campus of Monash University.

5.45pm-6.15pm: Refreshments, Menzies building, Monash University.

6.15pm-7.15pm: Room E365, Menzies building, Monash University.

A New Statistical Framework for Assessing Health Impacts of Environmental Mixtures

The traditional statistical approach to studying the health impacts of complex environmental mixtures has been to select individual components and adjust for the presence of other components. This approach allowed for the straightforward translation of research on health effects to interventions or policies. If pollutant X is harmful, then we should reduce exposure to pollutant X. This inherent directionality induced by the one-dimensional nature of the exposure has the benefit that it can lead to a clear next step. Considering sets of pollutants as exposures introduces multi-dimensional measurements whose values do not lie on an ordered line, but rather in an unordered high-dimensional space. The geometry of the multi-pollutant exposure space removes the natural directionality of the single pollutant approach, breaking the simplicity that had previously connected health effects research and potential interventions. We propose a statistical approach for estimating the health impacts of complex environmental mixtures by introducing the concept of a composition-altering contrast, which is any comparison, intervention, policy, or natural experiment that can be used to observe a mixture’s composition in multiple states. Composition-altering contrasts allow us to (a) link changes in mixture composition to observed and interpretable changes in the environment; (b) assess the health effects of mixtures associated with those changes in composition; and (c) embed our analysis in a framework that allows for causal interpretations of estimated effects.

Roger D. Peng is a Professor of Biostatistics at the Johns Hopkins Bloomberg School of Public Health. His research focuses on the development of statistical methods for assessing the health impacts of environmental exposures and he has published extensively on the health effects of indoor and outdoor air pollution, extreme heat, and climate change. He is also a co-founder of the Johns Hopkins Data Science Specialization (, the Simply Statistics blog ( where he writes about statistics for the general public, the Not So Standard Deviations ( data science podcast with Hilary Parker, and The Effort Report ( podcast with Elizabeth Matsui. He is a Fellow of the American Statistical Association and the recipient of the 2016 Mortimer Spiegelman Award from the American Public Health Association, which honors a statistician who has made outstanding contributions to public

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