Sunday, June 29, 2025

What is a shockDecomposition()?

 


The Nixon Shock of 1971 was an attempt to stop inflation by ending convertibility of the US Dollar into Gold. Along with other forms of economic Shock Therapy, is (from the standpoint of Systems Theory) an attempt to pop Economic Bubbles and return the system to a sustainable attractor path. But economies are subject to all sots of shocks and the general question for analysis is how do feedback effects operate in the presence of shocks. The way to study the effects of shocks on a system is called Shock Decomposition And, if you have a computer model, shock decompositions can be studied through computer simulation.

What a shock decomposition will show you depends on (1) what parts of the system are being shocked and (3) the internal dynamics (if any) of the computer model. To focus this discussion, I am going to concentrated on systems and state space models since any system can be put in state space form (see the discussion here).

Take a very simple state space (SS) model:


The SS model state equation (line 1 above) will have p state variables and  m input variables.