You can't really criticize it only based on those numbers, at least not without looking at similar numbers from other cohort studies with the same length.
Well, one can't criticize the quality of the study without looking how well other studies did. But even if all studies involve a massive drop-out rate, the drop-out rate still seems like something to look at in evaluating the accuracy of the study.
I mean my concern, looking from the outside, isn't relative accuracy, but absolute accuracy. Not "is it as good as other studies?" but "it is good enough that I can rely on it?"
15 -years- is a LONG time for a study. I'm not sure about the dropout rates, but it is a real statistical issue. I'm just not sure there's anything that can reasonably be done about it. You'd have to have something like federally mandated participation / continued participation. That's also very unlikely to pass ethics boards.
BTW, it would also be an issue if the subjects were compensated to the point that they differed from the actual population at large.
Fundamentally having more respect for doing things right, the right way, over the /long/ term, including the STEM fields, would be a 'good thing' for any society, but particularly western ones (where often the bad/evil antagonist is based on science or a cold lack of emotions; but the protagonist is based mostly on emotion and feeling instead of logic).
15 -years- is a LONG time for a study. I'm not sure about the dropout rates, but it is a real statistical issue. I'm just not sure there's anything that can reasonably be done about it.
Everyone keeps replying as if my comments imply a demand that "something be done about this". That's not my point. Maybe nothing can be done about it. The situation is still significant or at least appears significant.
Similarly, it may be that running studies like this is really difficult and that massively reduced sample sizes are something we must accept for practical reasons... but that doesn’t mean it permits us to ignore statistical ramifications
Well, one can't criticize the quality of the study without looking how well other studies did. But even if all studies involve a massive drop-out rate, the drop-out rate still seems like something to look at in evaluating the accuracy of the study.
I mean my concern, looking from the outside, isn't relative accuracy, but absolute accuracy. Not "is it as good as other studies?" but "it is good enough that I can rely on it?"