“…Various methods have been investigated for computing the Sobol' indices based on Monte Carlo simulation (Archer et al, 1997;Sobol', 2001;Saltelli, 2002;Sobol' and Kucherenko, 2005;Saltelli et al, 2010); because of the large number of model evaluations required, these methods are not affordable for computationally costly models. To overcome this limitation, more efficient estimators have recently been proposed (Sobol et al, 2007;Janon et al, 2013;Kucherenko et al, 2015;Owen, 2013). A different approach is to substitute a complex model by a meta-model, which has similar statistical properties while maintaining a simple functional form (see e.g.…”