Prof. Harrell has wisely suggested moving another twitter discussion on statistics here. The original discussion is found here (https://twitter.com/RogueRad/status/1074730161617231873)
There are several issues:
(1) The initial tweet seems to suggest that it is reasonable to analyze change in a continuous outcome (weight) in each arm of an RCT separately (i.e. final-initial, presumably with a one sample t-test). To me this seems very wrong. I would think that an ANCOVA to estimate the between group difference in final weight, adjusting for baseline weight and possibly other things, is what we really want, but I would appreciate input from others.
(2) A deeper debate arose from the construction of this example with markedly different variances in each arm. I would think this would be very unlikely in an RCT unless there was significant heterogeneity of treatment effect or ceiling/floor effects or a smallish sample size with random variation. Am I missing something?