What inspired this wish list request?
The Fit Y by X platform cannot analyze data from a Randomized Incomplete Blocks Design (RICBD), i.e. if the blocks are unbalanced, i.e. 1 plot (or more) is missing in 1 block (or more), and therefore in JMP 18, the Fit Y by X automatically invoked SLS in Fit Model platform, and that what users needed!
Unfortunately, this very important and very useful feature was removed in JMP 19,and JMP invokes a mixed model in Fit Model platform instead, in order to allow for a valid test for Unequal Variances.
What is the improvement you would like to see?
Simply return the way this issue was handled in JMP 18.
Or as an alternative (less-preferred) option, allow an option (e.g. in Oneway Preferences Menu) for JMP to handle the Randomized Incomplete Blocks Design case with Fit Model - Fit SLS (the same way it is handled in JMP 18; i.e. with no Unequal Variances test available).
Why is this idea important?
Many researchers using Fit Oneway are not familiar with Mixed Modeling approaches and may not understand that JMP is treating block as a random factor (not a fixed factor), with an unequal variance structure (repeated on the X factor). Researchers, Scientits, and Engineers using Fit Oneway often prefer and are most familiar with the simplest (least technically or statistically complex) model, and the equal variance assumption can often be appropriate for their experimental situation.
Allowing JMP users to Fit the SLS regression model for RICBD in Fit Oneway gives these users the most flexibility without leaving the platform, since now to fit the arguably simpler model, they have to go to Analyze > Fit Model and specify the SLS regression model there.