HKSM

A quantitative assessment of the likely costs to complete project work at the activity, work package, or project level. Estimates may be single-point values or ranges and should state the method, assumptions, data sources, and confidence.

Key Points

• Quantifies expected costs for defined scope items, often with ranges that reflect uncertainty.
• Common methods include analogous, parametric, bottom-up, three-point estimating, and vendor bid analysis.
• Should cover direct and indirect costs, fixed and variable costs, and one-time and recurring expenses.
• Include contingency for known-unknown risks; management reserve is controlled by leadership and not embedded in activity estimates.
• Quality depends on clear scope, reliable data, expert judgment, and documented estimating basis.
• Refined iteratively as information improves and risks are addressed (progressive elaboration).

Purpose of Analysis

The goal is to develop credible, decision-ready cost figures that enable budgeting, trade-offs, and funding approvals.

• Support creation of the cost baseline and cash flow forecasts.
• Inform make-or-buy, scope, schedule, and risk-response choices.
• Provide a defensible basis for stakeholder negotiations and approvals.
• Enable contingency planning and reserve allocation.

Method Steps

• Define estimate scope: identify activities/work packages from the WBS and clarify assumptions and constraints.
• Select estimating approach per item: analogous, parametric, bottom-up, three-point, or vendor bids.
• Gather data: historical information, productivity rates, resource rates, quotes, and risk data.
• Estimate at the lowest practical level; document methods, assumptions, data sources, and calculation logic.
• Incorporate risk: apply ranges or three-point values and calculate contingency based on risk analysis.
• Aggregate to higher levels (work package, control account, project) and check for omissions or double-counting.
• Review with SMEs and stakeholders; refine and baseline when appropriate, then update as changes occur.

Inputs Needed

• Scope baseline, WBS, and WBS dictionary.
• Resource requirements and resource rate information.
• Project schedule or activity list with durations and sequencing.
• Risk register and risk analysis results.
• Historical data, lessons learned, and organizational estimating policies.
• Market rates, vendor quotes, and procurement information.
• Assumptions, constraints, and stakeholder cost expectations.

Outputs Produced

• Activity or work package cost estimates (single values or ranges with confidence levels).
• Documented estimating basis (methods used, data sources, assumptions, constraints, and range/accuracy).
• Recommended contingency reserves tied to identified risks.
• Updates to risks, assumptions, and lessons learned based on estimating insights.

Interpretation Tips

• Prefer ranges with stated confidence over single-point values, especially early in the project.
• Check if estimates include or exclude contingency, indirect costs, taxes, and inflation.
• Validate drivers (e.g., labor hours, productivity, materials) and compare with benchmarks or past projects.
• Watch for optimism bias; use three-point or reference class data to counter it.
• Align estimates to the WBS to ensure full scope coverage and traceability.
• Update estimates as scope or risk changes to keep the cost baseline realistic.

Example

For a work package requiring 200 labor hours at 60 per hour and materials at 4,000, the deterministic estimate is 200 × 60 + 4,000 = 16,000. Using three-point data for labor hours (O = 180, M = 200, P = 240), the expected hours are (180 + 4×200 + 240) / 6 = 203.3 hours, giving 203.3 × 60 + 4,000 ≈ 16,200. If risk analysis indicates a 10% contingency, the range could be 16,200 ± 10%.

Pitfalls

• Using a single-point estimate without stating its range or confidence.
• Ignoring indirect costs, overhead, taxes, or currency effects.
• Relying on outdated rates or poor-quality historical data.
• Double-counting scope or reserves when aggregating estimates.
• Failing to involve appropriate subject matter experts and suppliers.
• Not documenting assumptions, leading to disputes and rework.

PMP Example Question

A project manager presents an activity estimate as 50,000 ± 20% with 75% confidence. What should the manager provide to best support stakeholder review of this estimate?

1. A detailed schedule network diagram.
2. The documented estimating basis, including methods, data sources, and assumptions.
3. A change request to add management reserve to the estimate.
4. A procurement plan with selected vendors.

Correct Answer: B — The documented estimating basis, including methods, data sources, and assumptions.

Explanation: Stakeholders need to understand how the estimate was developed and what it includes to judge credibility and risk. The estimating basis clarifies approach, inputs, ranges, and confidence.