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The paper analyses the difficulties of performing sensitivity analysis on the output of complex models. A number of selected non-parametric statistical techniques are applied to model outputs without assuming knowledge of the model structure. The techniques employed are mainly concerned with the analysis of the rank transformation of both input and output variables. The test models taken into consideration are three benchmarks of the Probabilistic System Assessment Code (PSAC) User Group. They describe nuclide chain transport through a multi-barrier system (near field, geosphere, biosphere) and are employed in the analysis of the safety of a nuclear waste disposal in a geological formation. Due to the large uncertainties affecting the system, these models are normally run within a Monte Carlo driver in order to characterise the distribution of the model output. A crucial step in the analysis of the system is the study of the sensitivity of the model output to the value of its input parameters. This study may be complicated by factors such as the complexity of the model, its non-linearity and non-monotonicity and others. The problem is discussed with reference to the three test cases and model non-monotonicity is shown to be particularly difficult to handle with the techniques employed. Alternative approaches to sensitivity analysis are also considered briefly.

Additional information

Authors: SALTELLI A, JRC Ispra (IT);HOMMA T, JAERI, Tokai Research Establishment, Department of Environmental Safety Research, Tokai-Mura, Ibaraki (JP)
Bibliographic Reference: Article: Computational Statistics & Data Analysis, Vol. 13 (1992) pp. 73-94
Record Number: 199210428 / Last updated on: 1994-12-02
Original language: en
Available languages: en