Why is the deficit cycle regular but unsmooth?

The Keynesians want to know. We have the deficit in blue, not smooth, and unemployment, much smoother.

Why is the blue unsmooth?
For starters we only publish the deficit on a year by year basis. The cycle mostly appear in a presidential cycle, along with the recessions.  They have sharp peaks.

Smoothness is determined by how well the logarithm is known, the natural log is the smoothing operator. Government only has a two year and four year look ahead, it is not smooth.

Yet unemployment, relative to the deficit is much smoother, the plan ahead is much more detailed, so the smoothing process involves longer look back and longer look ahead.


Why do presidential cycles seem to line up with recessions?

Oil suppliers do not smooth savings, they suffer the Dutch disease:

In economics, the Dutch disease is the apparent relationship between the increase in the economic development of natural resources and a decline in the manufacturing sector (or agriculture).

So oil suppliers around the world save by keeping oil in the ground.  When the government runs deficits,  oil exporters do not invest in bonds as much as manufacturing exporters. So oil supplies are heavily influenced by the dollar value, and sudden tax changes in DC cause exchange rate changes and oil supply disruptions.