I wonder if the GC-MS exists for municipal water supplies already, and can just be aggregated and compared against population obesity rates? Less precise than doing it house-by-house, but much cheaper if someone has already done it for you and also it might not vary much house-by-house.
Yes, that is what I meant by geographic units. It has both advantages and disadvantages: data may already be available, and may be much more statistically-powerful; on the other hand, variance-components like BLUP usually are done with individuals available, and I’m not sure about the interpretation/correctness of doing it otherwise.
I wonder if the GC-MS exists for municipal water supplies already, and can just be aggregated and compared against population obesity rates? Less precise than doing it house-by-house, but much cheaper if someone has already done it for you and also it might not vary much house-by-house.
Yes, that is what I meant by geographic units. It has both advantages and disadvantages: data may already be available, and may be much more statistically-powerful; on the other hand, variance-components like BLUP usually are done with individuals available, and I’m not sure about the interpretation/correctness of doing it otherwise.