Investing tens of millions in experiments based on a hypothesis that you don't really test is stupid.
The hypothesis being tested is that the blood level of vitamin D is relevant for the outcomes. You think they should test another hypothesis but that doesn't mean the original researchers are stupid.
The empirical method. You can take different amount of vitamin D and see the effect on yourself.
If I am interested in the effect of vitamin D on overall mortality, it's kinda difficult to "see the effect on [my]self".
Coming to your own judgments instead of trying to follow what some authoritative doctor or doctrine tells you is what Kant described in his day's as his ideal of enlightenment.
Yes, but you're confused between blindly following authority and looking at data from people other than yourself.
The hypothesis being tested is that the blood level of vitamin D is relevant for the outcomes. You think they should test another hypothesis but that doesn't mean the original researchers are stupid.
I didn't call individuals stupid but I spoke about the practice they follow. I also don't call 18st century scientists stupid even when a lot of their mental models were stupid from the perspective of knowing what I know today.
In this case, before you spend a lot of money on a long term mortality study it's better to run a few smaller studies to gauge whethe...
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.