> What is the alternative explanation for why semaglutide would disincline people who would have had small change scores from participating or incline people who have large change scores to participate (remember, this is within-subjects) in the alcohol self-administration experiment?
I’m a bit unsure what the non-alternative explanation is here. But imagine that semaglutide does not reduce the urge to drink but—I don’t know—makes people more patient, or makes them more likely to agree to do things doctors ask them to do, or makes them more greedy. Then take the “marginal” person, who is just on the border of participating or not. If those marginal people drink less on average, then semaglutide would look good purely due to changing selection rather than actually reducing drinking.
Now, I don’t claim that the above story is true. It’s possible, but lots of other stories are also possible, including ones where the bias could go in the other way.
I also think there is a general tendency for people to believe that once they’ve identified a selection issue the results are totally undermined.
I expected this sentence to be followed by you praising me for explicitly disavowing such a view and stating that, since the bias could be in either direction, the lab experiment does provide some evidence in favor of semaglutide. :) (Just very weak evidence.)
(Sorry for the slow reply—just saw this.)
> What is the alternative explanation for why semaglutide would disincline people who would have had small change scores from participating or incline people who have large change scores to participate (remember, this is within-subjects) in the alcohol self-administration experiment?
I’m a bit unsure what the non-alternative explanation is here. But imagine that semaglutide does not reduce the urge to drink but—I don’t know—makes people more patient, or makes them more likely to agree to do things doctors ask them to do, or makes them more greedy. Then take the “marginal” person, who is just on the border of participating or not. If those marginal people drink less on average, then semaglutide would look good purely due to changing selection rather than actually reducing drinking.
Now, I don’t claim that the above story is true. It’s possible, but lots of other stories are also possible, including ones where the bias could go in the other way.
I expected this sentence to be followed by you praising me for explicitly disavowing such a view and stating that, since the bias could be in either direction, the lab experiment does provide some evidence in favor of semaglutide. :) (Just very weak evidence.)