Quote:
Originally Posted by Vael
Why does a covariance of greater than one suggest positive correlation and a covariance of about one no correlation??
|
I made a mistake in my characterization; I'm claiming that Cov(length of time in recession, date went off gold standard)/Var(date went off gold standard) = 1 in reality, while Murphy's story would predict Cov(length of time in recession, date went off gold standard)/Var(date went off gold standard) > 1. The interpretation is that a regression of (length of time in recession) on (date went off gold standard) would have a coefficient of approximately one, whereas Murphy's model would predict a regression coefficient of greater than one.
In any case, in both cases, the correlation is non-zero (and in fact may equal unity); remember that I'm comparing the covariance of (length of time in recession, date went off gold standard), not (length of time in recession _after_ going off gold standard, date went off gold standard); the latter indeed approximates zero (in reality, not in Murphy's story).
Yes, I was being more confusing than I should have been.