"The Fed's monetary base (M0) and fertility rates show a strong negative correlation (-0.899, p < 0.001) – the kind of relationship you rarely see in social systems." - this is confounded by "point in time". When you have any two time-dependent variables (e.g. stork population and number of babies over time), and the first one goes down and the second one goes up monotonically over a period of time, you get a correlation of -1^C^C a strong negative correlation, and -1 in case they are both linear -- and get "strong evidence" for the theory that storks bring babies.
For more meaningful evidence, one needs to get data over multiple places at the same time. For a start, do countries in East Asia, with particularly low birth rate, print particularly large amounts of money?
"The Fed's monetary base (M0) and fertility rates show a strong negative correlation (-0.899, p < 0.001) – the kind of relationship you rarely see in social systems." - this is confounded by "point in time". When you have any two time-dependent variables (e.g. stork population and number of babies over time), and the first one goes down and the second one goes up monotonically over a period of time, you get a correlation of -1^C^C a strong negative correlation, and -1 in case they are both linear -- and get "strong evidence" for the theory that storks bring babies.
For more meaningful evidence, one needs to get data over multiple places at the same time. For a start, do countries in East Asia, with particularly low birth rate, print particularly large amounts of money?