" If you manage a complex organization as if it were just a complicated one, you’ll make serious, expensive mistakes.”

Most of the approaches used to address complex system are approaches for complicated system ( Six Sigma, Balance Scorecard, …).

But how to work in a complex system ?  

According to Gökçe Sargut and Rita Gunther McGrath , they recommend to:
· Improve the way you forecast by using tools/models that simulate the behavior of the system. Process Behaviour Chart (see Shewart)
· Improve the way you mitigate risk by minimizing the need to rely on predictions/expectations to experiment, by…
· Make different resource tradeoffs by providing diversity of thoughts and by investing in incremental and small investment in new project/approaches.

They describe some of the essential parts of " a system of profound knowledge" :
  • appreciation for a system, 
  • knowledge about variation, 
  • theory of knowledge, and 
  • psychology. 
The system of profound knowledge is a complex system as we've to consider it a a network of interdependent components that work together to accomplish the purpose of the system.
The  4 interrelated parts can't be understood if separated from one another.
As Deming said : "Rational prediction requires theory and builds knowledge through systematic revision and extension of the theory based on comparison of prediction with observation."(Deming, The New Economics). 
The system of profound knowledge is based on the premise that management is prediction.  
If we fail to predict what we expect  ("Theory), we fail to predict the results of our experiment to improve, we fail to analyze the results of our experiment and we fail to learn about our system.
So we don't improve.