lsmeans not estimable, but lsmean differences are [R for BE/BA]

posted by d_labes  – Berlin, Germany, 2019-03-03 14:07 (725 d 11:43 ago) – Posting: # 19988
Views: 1,501

Dear ElMaestro,

» So, R is telling me that it can derive a difference of lsmeans but it can't derive the lsmeans individually. I find this quite annoying, possibly hard to believe.

With the last sentence I agree totally.
Nevertheless such situations exist :yes:.

I have sometimes encounter this situation in SAS using the LSMeans statement in Proc GLM.

See the FAQs for emmeans for an R implementation. Look under point 8.

Why this is so precisely is beyond my intellectual reach. Had to tackle such things like "estimability theory". Oh my dear!

My own explanation, quick and dirty only for myself, goes like this: Some factors constellations used in LSMeans which lead to the NonEst result cancel out if you derive LSMeans for the difference and therefore the latter are estimable.

Regards,

Detlew

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