Bioequivalence and Bioavailability Forum

Huge gap in my understanding [General Statistics]

posted by ElMaestro – Denmark, 2018-03-04 11:03 (2683 d 14:13 ago) – Posting: # 18494
Views: 6,119

Hi all,

Here's where I am so far:

When we deal with the standard BE model the LSMEan difference of T and R equals the treatment effect difference, regardless of contrast coding. We thus do not need to worry about LSMeans to construct the 90 or whatever % CI around the geo LSMean ratio. We just extract the treatment effect difference from the effect vectors (=the model coefficient).
If we introduce a covariate, however, the LSMean difference may not be the same as the treatment effect difference. This implies that the LSMean difference is not necessrily the maximum likelihood difference. This to me is a big, big worry. I consider this a huge gap in my understanding. Why would that be so, and what would be factual advantage (whether practical or theoretical) about a CI built around something which is not the maximum likelihood treatment difference? I did not extensively play around with contrast coding. Yet.

Hilfe, what is going on here? I hope someone will explain and discuss and go a little beyond applying some contrasts.
Many thanks.

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Pass or fail!
ElMaestro