If an experimenter assigns subjects to an experimental vs a control group truly randomly, is there still any point to performing baseline comparisons between the groups, after they've been so defined?
To me this seems very strange, but I see it done quite often in clinical psychology papers (example, p.4). Were a baseline difference to be found, it seems that either ignoring it or messing around with the group allocation to make the groups "truly" equivalent on whatever measure of interest, would both be dodgy practices. So, should such a check even be made, by (perhaps) thinking of it as a manipulation check?
In a previous question I asked, one contributor very nicely exaplained the role of random assignment:
At the population level, this is, in fact, impossible. That's the value of random assignment. When subjects are randomly assigned to conditions, then the conditions must be drawing on the same population, because the assignment to conditions is guaranteed to be independent of any features of the subjects. Any population difference in outcomes must be causal effects of the conditions themselves, and nothing prior to that.
It seems to me checking for group differences immediately after assigning subjects to a treatment and control groups, defeats the purpose of why we do random allocation to begin with. Am I wrong?