Hello,@ConnectedSystems.

Sure, it would be great to help, but this week I'm a little too busy with my PhD thesis. I can work on this in about 1 week, if it's not too late.

Thanks,@lbteixeira

There's no deadline and so. no rush. I'll come back to this myself in a week or so as well.

One thing to consider with grouping approaches is that you can get cancellation effects. Morris uses an average of absolute elementary effect when computing sensitivity indices for groups, rather than the average.

For example with two parameters in one group, if one parameter has a strong positive effect, and another a strong negative effect, these will cancel out when averaged and the group will seem to have a negligible effect.