VARS-TOOL: A toolbox for comprehensive, efficient, and robust sensitivity and uncertainty analysis

Saman Razavi, Razi Sheikholeslami, Hoshin V. Gupta, Amin Haghnegahdar

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


VARS-TOOL is a software toolbox for sensitivity and uncertainty analysis. Developed primarily around the “Variogram Analysis of Response Surfaces” framework, VARS-TOOL adopts a multi-method approach that enables simultaneous generation of a range of sensitivity indices, including ones based on derivative, variance, and variogram concepts, from a single sample. Other special features of VARS-TOOL include (1) novel tools for time-varying and time-aggregate sensitivity analysis of dynamical systems models, (2) highly efficient sampling techniques, such as Progressive Latin Hypercube Sampling (PLHS), that maximize robustness and rapid convergence to stable sensitivity estimates, (3) factor grouping for dealing with high-dimensional problems, (4) visualization for monitoring stability and convergence, (5) model emulation for handling model crashes, and (6) an interface that allows working with any model in any programming language and operating system. As a test bed for training and research, VARS-TOOL provides a set of mathematical test functions and the (dynamical) HBV-SASK hydrologic model.

Original languageEnglish (US)
Pages (from-to)95-107
Number of pages13
JournalEnvironmental Modelling and Software
StatePublished - Feb 2019


  • Dynamical systems models
  • Global sensitivity analysis
  • Morris
  • Performance metrics
  • Progressive Latin hypercube sampling (PLHS)
  • Sensitivity indices
  • Sobol’
  • Uncertainty analysis
  • Variogram analysis of response surface (VARS)

ASJC Scopus subject areas

  • Software
  • Environmental Engineering
  • Ecological Modeling


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