Representing Statistical Distributions for Uncertain Parameters in LCA

Introduction. Statistical information for LCA is increasingly becoming available in databases. At the same time, processing of statistical information is increasingly becoming easier by software for LCA. A practical problem is that there is no unique unambiguous representation for statistical distributions. Representations. This paper discusses the most frequently encountered statistical distributions, their representation in mathematical statistics, EcoSpold and CMLCA, and the relationships between these representations. The distributions. Four statistical distributions are discussed: uniform, triangular, normal and lognormal. Software and examples. An easy to use software tool is available for supporting the conversion steps. Its use is illustrated with a simple example. Discussion. This paper shows which ambiguities exist for specifying statistical distributions, and which complications can arise when uncertainty information is transferred from a database to an LCA program. This calls for a more extensive standardization of the vocabulary and symbols to express such information. We invite suppliers of software and databases to provide their parameter representations in a clear and unambiguous way and hope that a future revision of the ISO/TS 14048 document will standardize representation and terminology for statistical information.