Local vs global sensitivity analysis with iTOUGH
Hello everyone,
I am currently attempting to conduct a local sensitivity analysis using iTOUGH. After going through the user's guide, it appears that the sensitivity analysis is primarily presented as a global sensitivity analysis. I would like to inquire whether iTOUGH is capable of performing sensitivity analysis, including the automatic calculation of derivatives, or if I need to handle this manually. If there is a method available, could you please provide a reference or example?
Thank you in advance for your responses.
Best regards,
what i mean with Local sensitivy vs Global sensitivy analysis :
Local analysis is based on calculating the effect on the model output of small perturbations around a nominal parameter value. Often the perturbation is done one parameter at a time thus approximating the first-order partial derivative of the model output with respect to the perturbed parameter.
The global analysis, on the other hand, seeks to explore the input parameters space across its range of variation and then quantify the input parameter importance based on a characterization of the resulting output response surface.
2 replies
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Hi Lam dor,
You probably read the special manual dedicated to global sensitivity analysis methods (even though the local sensitivity analysis method is also described in Section 2.1 of that report).
iTOUGH2 calculates local sensitivity coefficients whenever it performs an inversion using a derivative-based minimization algorithm. A standard local sensitivity analysis is available in iTOUGH2, including the calculation of composite sensitivity measures. It is demonstrated in the very first iTOUGH2 sample problem (Part 3). All manuals are available at https://tough.lbl.gov/documentation/tough-manuals/ or https://www.finsterle-geoconsulting.com/publications.
Stefan