There seems to be growing interest in the scientific and ethical merits of using an adaptive or platform design for clinical trials, particularly in the setting of large scale #COVID19 international collaboration. Are there any drawbacks?
The problem is some variation is random, so unusual benefits or harms could be due to chance alone. The idea of "regression to the mean" is where unusual results become less unusual over time as the effect of random outliers is diminished over time. bmcmedicine.biomedcentral.com/articles/10.11…
This is an interesting data analysis showing the recent case north of Seattle appears to be from a strain related to an earlier case in WA state, a relationship that does not appear to be due to chance alone. @trvrb suggests 6 weeks of transmission there
This would not be unexpected since we know the disease is fairly contagious and difficult to contain. Thus, in addition to modeling, I'm confident local authorities will work on old fashioned contact tracing and may discover if the two cases connect.
Another explanation would be a separate introduction from the same strain. Travel itself is non-random, so individuals traveling between Snohomish county & China could have both non-randomly interacted with people infected with the same strain in China