4.2.3: Step 3 – Effort and Duration Estimation

🎯 Purpose of This Section

Once your work has been broken down and sequenced, it’s time to ask the next critical question:

“How long will each task take—and how much effort will it require to complete?”

Effort and duration estimation allows you to:

• Forecast resource usage

• Build a timeline based on capacity and availability

• Anchor your milestones to real-world task completion

• Understand whether your schedule is feasible

This section turns your WBS and sequencing logic into a credible forecast for execution.

🧠 Key Definitions

Term	Definition
Effort	The amount of work required to complete a task, usually measured in staff hours (e.g., 10 hours of analyst time)
Duration	The number of calendar days needed to complete a task, factoring in availability, coordination, and delays
Availability	The percentage of a team member’s time that can realistically be devoted to this task (e.g., 50% if split across other projects)

💡 Effort is about how much work is required. Duration is about how long it will take. They are related—but not the same.

🛠️ Step-by-Step: How to Estimate Effort and Duration

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🔹 Step 3.1 – Pull Your Level 3 Task List

Use your WBS (Section 1) and dependencies (Section 2) to prepare a full list of actionable tasks that need estimates.

Create a table with the following headings:

WBS ID	Task Name	Effort (hrs)	Duration (days)	Notes / Assumptions

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🔹 Step 3.2 – Choose an Estimation Strategy

Choose the estimation method that best fits each task. You can mix methods based on what you know:

✅ Expert Judgment

• Ask a team member or SME how long similar work has taken in the past

• Use when: you have direct experience or a known benchmark

✅ Historical Data

• Use documentation or records from previous projects

• Use when: similar projects have been tracked and archived

✅ Parametric Estimating

• Apply a known rate:

“Each interview takes 2 hours. We need 8 interviews = 16 hours.”

• Use when: you’re doing repeated or scalable tasks

✅ Three-Point (PERT) Estimation

• Estimate Optimistic (O), Most Likely (M), and Pessimistic (P)

• Use the formula:

Expected = (O + 4M + P) ÷ 6

• Use when: high uncertainty exists or tasks depend on external inputs

📘 Example:

Draft training material
O = 6 hrs, M = 10 hrs, P = 20 hrs
Expected = (6 + 4×10 + 20) ÷ 6 = 11.6 hrs

🔹 Step 3.3 – Assign Effort to Each Task

For each Level 3 task:

• Enter a realistic effort estimate (in hours)

• Round up to account for coordination or rework

• Be conservative, but not inflated—plan to your team’s skill level

📘 Tip:

• Short tasks: 2–4 hrs

• Medium: 6–16 hrs

• Long: break into subtasks if over 20 hrs

🔹 Step 3.4 – Calculate Duration Based on Availability

Use this formula:

Duration = Effort ÷ Daily Availability

Assume:

• Full-time availability = ~6–7 productive hrs/day

• Stakeholder or vendor delays will extend duration

• Weekends, holidays, and multitasking impact delivery

📘 Example:

• Task: Create implementation guide
  Effort: 18 hrs
  Analyst is available 6 hrs/day → Duration = 3 days
  If analyst is split 50% time → Duration = 6 days

🔹 Step 3.5 – Document Assumptions and Risks

Every estimate should have an explanation, especially for:

• Long tasks

• Tasks that depend on stakeholder response

• Tasks in unfamiliar domains

📘 Example:

Assumes interviewees are scheduled with no cancellations. If rescheduling occurs, add 2 days.

Good estimation is not just about the numbers—it’s about the thinking behind the numbers.

🧠 Pro Tips for Strong Estimating

• Never estimate in a vacuum—discuss with your team or peers

• Round to the nearest half-hour or day—avoid excessive precision

• Break down any task larger than 20 hours

• Use ranges or PERT estimates for uncertain tasks

• Validate total effort per phase—does it align with your scope?

❌ Common Pitfalls to Avoid

• Underestimating review cycles or feedback loops

• Forgetting to account for partial availability

• Skipping over high-risk tasks (“we’ll figure it out later”)

• Making all tasks the same size (e.g., every task = 8 hrs)

• Giving no explanation for outliers (why is this one 40 hours?)

📄 What You Will Submit

Submit a clean table or spreadsheet with:

Task ID	Task Name	Effort (hrs)	Duration (days)	Notes / Assumptions
2.1.1	Draft Requirements Doc	16 hrs	3 days	Assumes internal review takes 1 day
2.1.2	Conduct Stakeholder Interviews	10 hrs	5 days	Based on 2 interviews/day

This output will:

• Feed directly into your milestone schedule

• Provide inputs for future resourcing

• Form the basis of delivery team workload planning

📋 Final Quality Check Before Submission

• Are all Level 3 tasks from your WBS included?

• Is each effort estimate backed by a method or rationale?

• Are durations realistic based on known availability?

• Are assumptions listed for any task that’s not obvious?

• Could a teammate or stakeholder understand and use this table?

If yes—your effort estimation is ready for scheduling and milestone planning.