I take exception to that American Enterprise Institute article,
A Fearful Symmetry: Six Decades of Treasury Yields for cutting off the chart at 1950,
for no explicitly stated reason. They simply talk about 1950 as if it were some obvious starting point. Endpoints are the very devil, and whenever someone fails to give a reason for choosing an endpoint I suspect the worst. I think they have done it because for some reason they want to present a narrative about a "fearful symmetry."
I have posted before on what I have called the "two-humped camel" (and, yes I'm putting spin on it, too, because I guess it is a 2-1/2-humped camel):
In a sense, I'm making the same point. Stocks are bad enough; a chart from Jim Otar which I won't post again--find it
here shows that, instead of thinking of 112 years of data as 112 data points, it is much more accurate to think of it as about 8 data points, each corresponding to one "secular" bull or bear market.
But bonds? We have 2-1/2 data points, and they are very different from each other. Even if you thought you knew the underlying dynamics and the statistical parameters, how do you estimate a statistical parameter with 2-1/2 data points?
Annual income twenty pounds, annual expenditure nineteen nineteen and six, result happiness; Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery.