Surely, the reasons are multivariate with all kinds of interactions and feedback mechanisms between the variables. It is really a good example of what natural

Surely, the reasons are multivariate with all kinds of interactions and feedback mechanisms between the variables. It is really a good example of what natural dimension reducers we are, even when we know it makes no sense. It is like we can't but help ourselves to reduce things to one explanatory variable. My favorite is the news headline "The market went up today because of X".