Hi All,
I have a question regarding Sobol index. I've calculated first order and total order indexes for a model. but I've got weird values for one input as the value for Sobol total order index is less than the first order one, while I expect that total order value should be at least equal (when there is no interaction) or more than the first order value.
On other other hand, I don't expect to get negative value for Sobol index which I got for this input parameters. Whether this means that there is a negative correlation between corresponding input parameter and the model output?
I would appreciate if anybody could help me with some advice.
Thank you very much