5.16 Estimate Activity Resources

5.16 Estimate Activity Resources
Inputs Tools & Techniques Outputs

Purpose & When to Use

This process figures out what resources each activity needs and in what quantities. Resources include people (skills and roles), equipment, facilities, and materials. Do this during planning, after defining activities and before estimating durations and costs. Revisit as scope changes, risks emerge, or availability shifts.

Mini Flow (How It’s Done)

  • Review scope and activities. Confirm the activity list, work packages, and assumptions.
  • Identify resource types. For each activity, list needed roles, skills, equipment, facilities, and materials.
  • Check availability. Consult resource calendars, functional managers, and vendor capacity to understand timing and constraints.
  • Estimate quantities and effort. Determine how many units and how much person-effort each activity requires.
  • Choose estimating techniques. Use analogous, parametric, bottom-up, or three-point estimates as appropriate.
  • Analyze options. Consider different skill mixes, in-house vs. external, equipment alternatives, and location or shift options.
  • Document the basis. Record methods, data sources, assumptions, constraints, and confidence levels.
  • Model schedule impacts. Note where resources drive activity duration (e.g., crew size) and flag potential bottlenecks.
  • Create or update the resource breakdown. Build a hierarchical view of resource categories to summarize needs.
  • Feed other plans. Provide inputs to schedule, cost, risk, procurement, and team plans; update activity attributes.

Quality & Acceptance Checklist

  • Every activity has defined resource types, skill levels, and quantities with dates or timing windows.
  • Effort and duration are distinguished, and crew size or equipment count assumptions are clear.
  • Resource calendars and availability constraints are referenced and current.
  • Alternative options and trade-offs were considered, with rationale recorded.
  • Basis of estimates includes methods used, data sources, and confidence ranges.
  • Dependencies on procurement or vendors are identified with lead times noted.
  • Resource-related risks and reserves are captured in the risk and contingency approach.
  • The resource breakdown structure is updated and aligns with the WBS and cost model.
  • Updates are reflected in activity attributes, schedule logic, and relevant management plans.
  • Stakeholders who supply resources (e.g., functional managers) have reviewed and agreed.

Common Mistakes & Exam Traps

  • Confusing effort with duration. More people rarely reduce duration linearly due to coordination overhead.
  • Skipping availability checks. Estimating headcount without calendars or manager input leads to unrealistic plans.
  • Ignoring non-human resources. Equipment, facilities, and materials can become the real constraint.
  • Assuming unlimited resources. Estimating as if resources are always on hand is a red flag on exams.
  • Jumping to acquire resources. This process estimates needs; securing people or vendors happens later.
  • Forgetting to document the basis. Missing assumptions and methods weakens estimates and auditability.
  • Leveling here. Resource optimization is typically handled during schedule development, not in estimation.
  • Not considering make-vs-buy options. Sometimes outsourcing or renting equipment is the better choice.
  • Overlooking skill mix and proficiency. Counting people without matching the required competencies causes rework.
  • Not updating risks and costs. Resource choices often change risk exposure and cost baselines.

PMP Example Question

A project’s testing activities require two specialized test rigs and three testers for two weeks. The functional manager can only provide two testers during that window. What should the project manager do first?

  1. Delay the testing activities until three testers are available.
  2. Revise the resource estimates by evaluating alternative options.
  3. Escalate to the sponsor to secure an additional tester.
  4. Start acquiring external contractors immediately.

Correct Answer: B — Revise the resource estimates by evaluating alternative options.

Explanation: In estimating, assess alternatives (e.g., different skill mix, equipment usage, shifts) and update the basis before making schedule or procurement moves. Decisions to delay, escalate, or acquire come after analysis.

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