According to the PMBOK® Guide, Expert Judgment is defined as judgment provided based upon expertise in an application area, knowledge area, discipline, industry, etc., as appropriate for the activity being performed.

Sources of Expertise: Expert judgment can come from many sources, including:

Other units within the organization.

Consultants and professional/technical associations.

Industry groups and subject matter experts (SMEs).

Customers or sponsors.

Application in Project Intervention: When a project manager faces a situation requiring " intervention " (such as a significant variance, technical failure, or strategic shift), they seek specialized knowledge to evaluate the inputs and provide recommendations. This is a primary tool used across almost all Process Groups, particularly in Develop Project Charter, Monitor and Control Project Work, and Perform Integrated Change Control.

Role of Industry Groups: Industry groups provide benchmarking data and best practices that are considered expert-level insights to ensure the intervention is aligned with current professional standards.

Comparison with other options:

A. Communication models: These are descriptions or schemas used to facilitate the exchange of information (e.g., sender-receiver models). They describe how information is sent, not the source of the professional recommendation.

B. Stakeholder participation: While consultants are stakeholders, the act of asking for a specific, knowledgeable recommendation is a technical application of " Expert Judgment " rather than just a general engagement or participation activity.

D. Enterprise environmental factors (EEFs): EEFs are the conditions, not under the immediate control of the project team, that influence, constrain, or direct the project (such as market conditions or organizational culture). While an industry group ' s standards might be an EEF, the act of requesting a recommendation is the use of the expert judgment tool.