Overview
Expert Judgment Estimation is a qualitative estimation technique that relies on the input, knowledge, and experience of individuals or groups with specialized expertise in a particular area. This method is valuable when historical data is limited or when dealing with unique or complex projects.
When to Use Expert Judgment
- Limited or no historical data available
- Unique or first-of-its-kind projects
- Rapidly changing technologies or methods
- Complex projects requiring specialized knowledge
- Validating estimates from other techniques
- Early project phases with high uncertainty
- Identifying risks and assumptions
Types of Experts
- Internal Experts: Team members with relevant experience
- External Consultants: Industry specialists or advisors
- Vendors: Suppliers with product-specific knowledge
- Subject Matter Experts (SMEs): Specialists in specific domains
- Experienced Project Managers: Those who have managed similar projects
Methods for Gathering Expert Judgment
Individual Consultation
- One-on-one interviews with experts
- Detailed discussion of assumptions and constraints
- Personalized estimates based on specific context
Delphi Technique
- Anonymous rounds of expert estimates
- Facilitator compiles and shares results
- Experts revise estimates based on group feedback
- Continues until consensus is reached
Group Brainstorming
- Collaborative session with multiple experts
- Open discussion of estimates and rationale
- Team reaches consensus through dialogue
Wideband Delphi
- Combination of individual and group techniques
- Experts review requirements independently
- Group meeting to discuss and refine estimates
- Anonymous re-estimation after discussion
Best Practices
- Select Appropriate Experts: Choose individuals with relevant, recent experience
- Provide Context: Share complete project information and constraints
- Avoid Bias: Use anonymous techniques when possible to prevent groupthink
- Document Assumptions: Record the reasoning behind estimates
- Use Multiple Experts: Gather diverse perspectives to reduce individual bias
- Combine Methods: Use expert judgment alongside data-driven techniques
- Review Regularly: Update estimates as experts gain project-specific knowledge
- Consider Confidence Levels: Ask experts to rate their certainty
Advantages
- Leverages valuable experience and insights
- Useful when data is unavailable or inadequate
- Can account for unique project factors
- Relatively quick to implement
- Helps identify risks and issues early
- Builds team buy-in and commitment
Disadvantages
- Subjective and potentially biased
- Quality depends on expert selection
- Can be influenced by organizational politics
- May lack transparency in reasoning
- Different experts may provide conflicting estimates
- Overconfidence in expert opinions can lead to errors
Improving Accuracy
- Cross-validate with multiple experts
- Combine with quantitative methods when possible
- Ask experts to explain their reasoning
- Review past estimates vs. actual results to calibrate
- Use structured techniques like Delphi to reduce bias
- Document lessons learned for future reference
Common Applications
- New technology implementations
- Custom software development
- Organizational change initiatives
- Research and development projects
- First-time vendor relationships
- Regulatory compliance projects
- Strategic planning initiatives
Hybrid Approaches
Often combined with:
- Analogous estimating for comparison
- Parametric estimating using expert-provided parameters
- Bottom-up estimating with expert input on tasks
- Three-point estimation using expert optimistic/pessimistic scenarios
