The decision quality framework has been useful for integrating decision analytic techniques into decision processes in a way that adds value. This framework extends to the specific context of portfolio decisions, where decision quality is determined at both the project level and the portfolio level, as well as in the interaction between these two levels. A common heuristic says that the perfect amount of decision quality is the level at which the additional cost of improving an aspect of the decision is equal to the additional value of that improvement. A review of several models that simulate portfolio decision-making approaches illustrates how this value added depends on characteristics of the portfolio decisions, as does the cost of the approaches.
Keisler, Jeffrey, "Portfolio decision quality" (2011). Management Science and Information Systems Faculty Publication Series. 43.