Aggregate, Disaggregate, and Hybrid Analyses of Ecological Risk Perceptions

24 Pages Posted: 8 May 2006

See all articles by Henry H. Willis

Henry H. Willis

The RAND Corporation

Michael L. DeKay

Carnegie Mellon University - H. John Heinz III School of Public Policy and Management

Baruch Fischhoff

Department of Engineering and Public Policy, Institute for Politics and Strategy, Carnegie Mellon University

M. Granger Morgan

Carnegie Mellon University - Department of Engineering and Public Policy

Abstract

Laypeople's perceptions of health and safety risks have been widely studied, but only a few studies have addressed perceptions of ecological hazards. We assembled a list of 39 attributes of ecological hazards from the literatures on comparative risk assessment, ecological health, environmental conservation and management, environmental psychology, and risk perception. In Study 1, 125 laypeople evaluated 83 hazards on subsets of this attribute set. Factor analysis of attribute ratings (averaged over participants) revealed six oblique factors: ecological impacts, human impacts, human benefits, aesthetic impacts, scientific understanding, and controllability. These factors predicted mean judgments of overall riskiness, ecological riskiness, acceptability, and regulatory strictness. In Study 2, 30 laypeople each evaluated 34 hazards on 17 attributes and 3 dependent variables. Aggregate-level factor analysis of these data replicated the appropriate portion of the factor solution and yielded similar regression results. Parallel analyses at the individual-participant level yielded factors that explained less variance in judgments of overall riskiness, ecological riskiness, and acceptability. However, the decrease in explanatory power was much less than is often reported for disaggregate-level analyses of psychometric data. This discrepancy illustrates the importance of distinguishing between the level of analysis (aggregate versus disaggregate) and the focus of analysis (distinctions among hazards versus distinctions among participants). In a hybrid analysis, aggregate-level factor scores predicted individual participants' riskiness judgments reasonably well. Psychometric studies such as these provide a sound empirical basis for selecting attributes of ecological hazards for use in comparative risk assessment.

Suggested Citation

Willis, Henry H. and DeKay, Michael L. and Fischhoff, Baruch and Morgan, M. Granger, Aggregate, Disaggregate, and Hybrid Analyses of Ecological Risk Perceptions. Risk Analysis, Vol. 25, No. 2, pp. 405-428, April 2005. Available at SSRN: https://ssrn.com/abstract=877119 or http://dx.doi.org/10.1111/j.1539-6924.2005.00599.x

Henry H. Willis (Contact Author)

The RAND Corporation ( email )

201 N. Craig St.
Pittsburgh, PA 15213
United States

Michael L. DeKay

Carnegie Mellon University - H. John Heinz III School of Public Policy and Management ( email )

Pittsburgh, PA 15213-3890
United States

Baruch Fischhoff

Department of Engineering and Public Policy, Institute for Politics and Strategy, Carnegie Mellon University ( email )

Baker Hall 129
5000 Forbes Avenue
Pittsburgh, PA 15213
United States
412-268-3246 (Phone)

M. Granger Morgan

Carnegie Mellon University - Department of Engineering and Public Policy ( email )

Baker Hall 129
5000 Forbes Avenue
Pittsburgh, PA 15213
United States

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