Population Ecology Based and Benefit Oriented Decision-making Model of Project Portfolio Scale

Firstly, by raising the question of decision-making of project portfolio scale, the attribute of population ecology to project portfolio is unveiled. Then, inspired by theories of population competition and interdependence, the project portfolio is classified into two types. Based on these two types, the TPPSD (transverse project portfolio scale decision-making) model and LPPSD (lengthways project portfolio scale decision-making) model are setup. The solution of models as n=2 are discussed, and the condition of stability of solutions is analyzed, the best scale of benefit of individual project under the condition of interactive influence and the best scale of benefit of project portfolio are achieved. By taking n=3 as an example, the operability of TPPSD model is verified