Authors: Vignes Gopal Krishna
The flow of research has illustrated the discussions on Rahn-Armey Curve and Metcalfe’s Law in describing the elements of Public Private Partnership by adopting the concept of animal spirits that were brought up by , ,and  and also other aspects of evolutionary economics. Besides that ,the connectivity between the complex structure of economic system and the degree of sustainable development play an important role in influencing the effectiveness of public private partnership projects under the theory of structural change. Balanced role of government (proper regulation and the supervision of projects proposals) and private sectors are still needed in the implementation of Public private partnership projects, which may enhance the level of meso trajectory phases of innovation (origination, diffusion and retention) and the latter concept is inline with  and .
Keywords: Meso-trajectory phases of innovation, Metcalfe’s Law, Rahn-Armey Curve, Public Private Partnership, Animal spirits