> Walter Willett has a whole chapter on this subject in his book Nutritional
> Epidemiology. It should be considered required reading before attempting to
> model anything that has to do with diet.
Thanks this is a really good book, not just for ppl wanting to study
nutrition but surveys in general as well as confounding and modifying
by multivariables.
(a simple guide) He has some really earth-moving examples of errors
commited in the past. As an example one group tried to find a
correlation between weight and disease as: disease=weight+blood
pressure+heart rate+blood cholesterol
and willett points out that they found no association because the
implications of "weight" cannot be separated from its effects on heart
rate etc.
Anyway I'm currently going on the definition of "adjusted" for 1 2 and
3 as the following equation:
adjusted variable=variable^-variable
(where variable-hat represents the variable predicted by 1 2 and 3 in
a multivariate equation and "variable" is just the actual variable.)
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