What inspired this request?
Space-filling designs in JMP (LHS, Max Entropy, Sphere-Packing…) treat all variables as freely settable, with no support for hard-to-change (HTC) factors. In many industrial simulation workflows — polymer processing, chemical engineering, CFD — some variables (e.g. reactor geometry, mixer configuration) are costly to change between runs, while others (formulation, operating conditions) are easy. There is currently no way to encode this split-plot-like structure in the Space Filling Design platform.
What improvement would you like to see?
Add a "Change Difficulty" column (Easy / Hard) in the Space Filling Design factor table, consistent with the existing HTC mechanism in Custom Design. When HTC factors are designated, the algorithm should group runs into whole-plot batches — HTC settings held constant within each group, ETC variables space-filled within each group, and HTC settings themselves space-filled across groups. Users should be able to control the number of groups and runs per group. Design diagnostics should report coverage both marginally (HTC and ETC separately) and jointly.
Why is this important?
The HTC structure is ubiquitous in industrial R&D and simulation-driven design, yet no major DOE software handles it natively in space-filling mode. Without this feature, users must either build the design manually outside JMP, use Custom Design with a space-filling criterion (less transparent), or ignore the constraint entirely. Supporting HTC variables in space-filling designs would make JMP uniquely capable for computer experiment workflows with grouped execution constraints — a growing use case in industries where surrogate modeling is standard practice.