Common Difficulties with Quick Estimates

How to estimate projects or features immediately based on a very high level of detail without the need of past experiences or analogies?

Break Down the Scope into Assumptions:

• Identify Key Components: Quickly identify the main components or features within the high-level scope.

• Make Assumptions Explicit: State the assumptions you're making about each component. For instance, if the scope is "develop a user authentication system," your assumptions might include the number of user roles, integration with external systems, and security requirements.

Use a Range-Based Estimation:

• Provide a Range Instead of a Single Number: Give a range (e.g., "This could take between 3 to 5 weeks") rather than a precise estimate. This allows for flexibility given the high-level nature of the scope.

• Base the Range on Complexity Factors: Use factors like the number of components, integration points, and unknowns to justify your range.

Outline Risks and Uncertainties:

• Highlight Unknowns: Clearly state what is unknown and how it could impact the estimate. For example, "If the integration with the third-party service requires custom APIs, the timeline could extend."

• Factor in Buffers: Include buffers to account for potential risks and uncertainties. Explain that this buffer is to manage risks related to the unknowns.

Engage in Quick Clarification:

• Ask Clarifying Questions: Even at a high level, ask one or two critical questions that could drastically affect the estimate. This shows you're considering the full picture and reduces the chances of overlooking significant elements

Present It as a Preliminary Estimate:

• Communicate the Preliminary Nature: Make it clear that this is an initial, high-level estimate that will need refinement as more details emerge.

• Set Expectations for Revision: Indicate when a more accurate estimate will be possible, perhaps after a brief discovery phase or after certain details are clarified.

Utilize Estimation Techniques:

• Use Rough Order of Magnitude (ROM): This method provides a high-level estimate with a wide confidence interval, typically used early in project planning.

• Apply PERT Analysis: If possible, use the Program Evaluation and Review Technique (PERT) by giving optimistic, pessimistic, and most likely estimates, then calculate a weighted average.