Objective project prioritization is the “Holy Grail” of project portfolio management practices.
Executives dream of an omniscient model that can be used to come up with accurate numerical rankings for all project requests such that project evaluation and decision making can be rendered academic.
Of course this is a pipe dream – at best, a prioritization model is an attempt to reduce some of the subjectivity around project evaluation but it can never be truly objective as it’s basis is usually on limited or flawed knowledge about the project requests themselves.
PPM derives a number of its principles from financial portfolio management and hence derives some of its weaknesses as well. Lack of full knowledge about an investment impacts our ability to invest in an optimal fashion. The best we can hope for is to hedge our bets through such techniques as diversification, dollar cost averaging, or analysis of fundamentals.
The same is true for project portfolio management – striving for a perfect priority ranking is less important than applying a consistent set of practices to understand relative priority. Anything more is a waste of effort.