5.12 Estimate Costs

5.12 Estimate Costs
Inputs Tools & Techniques Outputs

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Purpose & When to Use

  • Develop a realistic view of how much the project work will cost so leaders can plan funding, compare options, and set expectations early.
  • Used during planning to estimate at activity or work package level, then refined as scope, design, and quotes mature.
  • Revisited when scope changes, risks evolve, procurement information arrives, or market rates shift.
  • Outputs inform the budget baseline process and provide the basis for future cost control.

Mini Flow (How It’s Done)

  • Collect inputs: scope baseline and WBS, activity list and durations, resource needs and rates, procurement strategy and quotes, risk register, lessons learned, cost policies, taxes, and currency assumptions.
  • Select estimating approaches: analogous for quick top-down comparisons, parametric for rate-based calculations, three-point for uncertainty, and bottom-up for detailed rollups.
  • Obtain market data and vendor pricing where relevant, and analyze bids when multiple offers exist.
  • Include quality-related costs, indirects, fees, and life-cycle considerations if required by the business case.
  • Calculate activity or work package costs, document assumptions and methods, and show ranges and confidence levels.
  • Apply risk-based contingency using reserve analysis, and identify any management reserve held by sponsors if applicable.
  • Aggregate estimates to work packages and control accounts aligned to the WBS, time-phase them to the schedule, and reconcile with funding limits.
  • Produce cost estimates and a clear basis of estimate, and update the risk register and documents as needed.

Quality & Acceptance Checklist

  • Each WBS item has an estimate that matches its defined scope and resources.
  • Chosen estimating methods are appropriate for the data available and are explained clearly.
  • Rates, units, and quantities are validated, current, and sourced.
  • Assumptions, constraints, and exclusions are documented and traceable.
  • Direct, indirect, procurement, logistics, taxes, and cost of quality are considered.
  • Currency, inflation, and escalation factors are addressed when relevant.
  • Risk-based contingency is calculated and linked to specific risks; no double counting with management reserve.
  • Estimates are time-phased and consistent with the schedule.
  • Estimate ranges and confidence levels are provided where uncertainty exists.
  • Peer review completed and stakeholder acceptance recorded.

Common Mistakes & Exam Traps

  • Confusing Estimate Costs (activity-level estimating) with Determine Budget (aggregating and setting the cost baseline).
  • Providing single-point numbers without a basis, range, or confidence level.
  • Ignoring indirect costs, cost of quality, or life-cycle impacts when required.
  • Mixing up contingency (for identified risks) with management reserve (for unforeseen work).
  • Double counting reserves or applying contingency at multiple rollup levels.
  • Using analogous estimates when detailed data is available for bottom-up or parametric methods.
  • Failing to refresh estimates after design changes or new vendor quotes.
  • Choosing the lowest bid without analyzing total cost of ownership and risk.
  • Overlooking currency conversions, inflation, or timing effects on cash flow.
  • Assuming earned value techniques are used during estimating rather than during monitoring and control.

PMP Example Question

The sponsor asks for a quick cost figure early in planning to compare alternatives. Detailed design is not yet available. Which technique is most appropriate?

  1. Analogous estimating.
  2. Bottom-up estimating.
  3. Vendor bid analysis.
  4. Earned value analysis.

Correct Answer: A — Analogous estimating.

Explanation: Analogous uses historical data for fast, top-down estimates when detail is limited. Bottom-up needs detailed scope, vendor bid analysis applies to procurements, and earned value is for performance tracking, not estimating.

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