feature request: estimated marginal means

[Geoff-Kahn]

As the title implies, I'm interested in calculating marginal means from the results of my pooled multilevel models. If would be wonderful to either see this functionality added to the mitml package, or have the ability to transform the results from testEstimates into an lmer object or something else that can be recognized by packages like emmeans.

[joshua-zh]

If I may, I would like to make a request for the marginal and conditional R squared. Thank you for your consideration.