A recent study in the Journal of Environmental Science and Technology reviews different methods for interpretation uncertainty in comparative LCAs. The study was led by Angelica Mendoza at CML in Leiden University. Our senior analyst, Valentina Prado, who co-authored this article, summarizes the study for us. The article is open access and can be accessed via this link.
What can we learn from uncertainty analysis results in a comparative LCA? This article reviews and applies five methods found in the literature designed to interpret uncertainty results in comparative contexts. This study provides LCA practitioners a guide and a platform to select and implement these methods.
It was found that there are two types of purposes: confirmatory and exploratory. Confirmatory purposes aim at determining statistical difference. These methods provide a binary type answer. It is focused in determining the existence of a difference no matter how big or small as long as it meets the chosen significance threshold (known as the P value). This can used for comparative assertions specifically footprints, to determine whether a product has indeed has a greater impact than another.
The other application of these methods is for exploratory purposes, to evaluate tradeoffs. The result of these approaches is a spectrum ranging from “most different”, to “least different” impact categories. Note that they do not establish significance. Rather it is used to identify those aspects that are most different among options.
Results show that methods agree with each other most of the time, with just a few exceptions which are due to two key properties: accounting for common uncertainties and accounting for the magnitude of the differences.
For confirmatory purposes, the modified NHST appears to be the most developed method as it accounts for the effect of sample size in the results (useful for simulation data) and incorporates a threshold to discard small differences. For exploratory purposes, there is no single method that takes into account the two properties mentioned above. The choice is between discernibility and the overlap area, out of which, authors recommend discernibility as they prioritize accounting for common uncertainties.
Presenter: Caroline Taylor
Caroline will discuss assessing the impact of investing in small businesses for sustainable development and social good as part of the large-scale US State Department investment in La Red de Innovacion e Impacto supporting Latin American micro, small and medium enterprises (MSMEs) using Sustainability Return on Investment (S-ROI).
Ever look at the stocks in a social impact investment fund and say to yourself, “what were they thinking?” Or go to an impact investing conference and hear people gushing over a soy-based product (because if it’s bio-based it can’t have any negative effects)? While things are slowly getting better, impact investors have a lot to learn when it comes to answering “what is sustainable?” The goal of this 3-hour workshop is to design a course targeting toward impact investors and giving them the knowledge that will help them make better choices in sustainable investments.
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