Hard-to-change factors

It would be nice to be able to set hard-to-change factors.

Sometimes a number of experiments can be run in parallel if one parameter is not changed.
It would therefore be good to have the option to set a specific factor(s) as hard-to-change.

Alternatively, if it was possible to create additional experiments with restrictions then that could also be a useful solution.

Start by reviewing the existing experiment and factor-configuration UI to understand how factors are currently selected and changed. Compare the two proposed directions: marking specific factors as fixed, or creating restricted experiments. Done means the chosen behavior is defined clearly and can be used to run parallel experiments without changing the selected factors.

Written by the indexing model from the issue text.