Expert judgment is a common entry in the tools and techniques used to perform the PMI processes. Like it sounds, it means making a decision, estimate or other activity choice based on the judgment of someone who is an expert in the area. For instance, an accountant who has worked on other, similar projects may give an estimate of how much a component will cost based on how much it has cost for recent projects. Or a software programmer may recommend a particular strategy according to what has worked well in the past. Expert judgment is one way to incorporate historical data into the planning and evaluation of a current project. Expertise may also be developed through training.

Examples of some of the processes where expert judgment may be helpful are