[quanto]

I agree with your ethos; too often poor science, regardless of kind, is being passed as "soft" or "applied" scientific research.

That said, I do think even noisy studies (noisy as in inaccurate measurements) like this at least show that there is no glaring big correlation between, say, low-carb diet and mortality. If low-carb diet people started to die decades younger than average, then even noisy studies would show. In this sense, studies like this have some value, albeit little.

[superqd]

I just think there is far too much noise in this sort of study to draw any sort of conclusion. An effect has to be very strong to manifest in such noise. Yeah, if the difference in life expectancy was 3 decades, say, then perhaps it would show in such noise.

[didibus]

What do you consider the "noise" here? That people would inaccurately assess if they were eating low-carb or not?