3 ms·
You're not the first to wonder about this. http://www.ncbi.nlm.nih.gov/books/NBK62370/ http://www.ncbi.nlm.nih.gov/books/NBK62370/ "It should be noted that whil
by brlewis 12y ago
You're not the first to wonder about this. http://www.ncbi.nlm.nih.gov/books/NBK62370/ http://www.ncbi.nlm.nih.gov/books/NBK62370/ "It should be noted that while these results may reflect the effect of exercise patterns on mortality, reverse causation is also possible—that the results reflect instead the effect of health on physical activity."
But what if you studied people who made a decision to change their exercise habits, and checked if it made a difference in general health?
- dragonwriter 12y agoThat would seem to be subject to the same basic problem; whether people make a decision to add exercise may well be strongly affected by their experience with activity eighth may be affected by the same kind of subclinical condition that itself is a mortality predictor discussed up thread. Of course the potential for such inverted causality is a cause for developing and testing hypotheses about the alternative explanations, not a reason to casually dismiss the study or the more obvious conclusion on the causal relationship.