No abstract

In many optimization situations, there are several responses associated with a product or process that need to be jointly considered. In this article we present Pareto front multiple objective optimization as an option to complement other statistical and mathematical methods in the response surface methodology toolkit. We demonstrate the Pareto front approach for multiple response process optimization based on evaluating a fine grid of input variable combinations within the range of operating conditions, as well as the use of a set of graphical tools to aid in decision making, with an example process involving two inputs and three responses of interest. We also discuss a simple way to examine the impact that variability in the responses can have on the solution by considering the estimated mean and worst-case response values. R code for implementing the methods discussed in this article is available upon request (jchapman@stlawu.edu).

No abstract

This work operationalizes the determinants of climate change risk, exposure and vulnerability, through the perceptions held by Native hunters, fishers, and gatherers in Savoonga and Shaktoolik, Alaska. Informed by their skill, experience, and the traditional knowledge of their elders, hunters, fishers, and gatherers in these communities are astute observers of their environment and environmental change. A questionnaire is used to sort and rank their perceptions of the most obvious and disruptive elements of climate change as representations of exposure and vulnerability, respectively. Results represent the relative strength and significance of those perceptions of environmental change. In addition to other changes, storms are among the most obvious and disruptive impacts of climate change to respondents in both communities, while changes to sea ice tend to be more disruptive in Savoonga, a more ice-obligate culture, than Shaktoolik. Changes on the tundra are more obvious in Shaktoolik, but is the least disruptive category of change in both villages. Changes along the coast were both obvious and disruptive, albeit more so in Shaktoolik than Savoonga. The findings suggest that traditional ecological knowledge is a valuable source of information to access perceptions of risk, and develop climate risk management and adaptation plans. The questionnaire design and statistical methodology may be of interest to those working on community-based adaptation and risk assessment projects in high-risk, poor, and marginalized Native communities with small populations.

Abstract:A two-stage Pareto front approach can improve the process of making a decision about which input values simultaneously optimize multiple responses. However, ignoring estimation uncertainty and natural variability in the responses can potentially lead to suboptimal choices about those input values. A simulation-based approach is used to quantify and examine the impact that variability has on the superior solutions identified on the Pareto front and their performance. Because each optimization scenario has its own unique characteristics, including responses with different amounts of natural variability, the impact of variability on the solutions varies from situation to situation. We study how varying the amount of response variability affects the locations identified for the front and the characteristics of the most promising solutions on the front. We illustrate the method with an application involving process improvement through variance reduction.