Estimate activity duration

📘 Estimate Activity Duration (Software Project Management)

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🔹 1. Definition

Estimating activity duration means predicting the amount of time required to complete a specific task or activity in a project.

👉 It answers the question: “How long will this task take?”

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🔹 2. Importance

• Helps create a realistic project schedule
• Ensures timely project completion
• Aids in resource planning
• Reduces chances of delays and cost overruns

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🔹 3. Factors Affecting Activity Duration

🔸 1. Task Complexity

• Simple tasks → less time
• Complex tasks → more time

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🔸 2. Resource Availability

• Skilled team → faster completion
• Limited resources → delays

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🔸 3. Experience of Team

• Experienced developers → accurate and faster work

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🔸 4. Technology Used

• Familiar tools → less time
• New technology → more time (learning curve)

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🔸 5. Dependencies

• Some tasks depend on completion of others

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🔹 4. Common Estimation Techniques

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🔸 1. Expert Judgment

• Based on experience of experts

👉 Example: Senior developer estimates coding time

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🔸 2. Analogous Estimation

• Based on similar past projects

👉 Example: Previous login system took 3 days → similar estimate used

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🔸 3. Parametric Estimation

• Uses mathematical models

👉 Formula:

Duration = Work / Productivity Rate

👉 Example: 100 pages ÷ 10 pages/day = 10 days

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🔸 4. Three-Point Estimation ⭐ (Important)

Uses three estimates:

• Optimistic (O) → Best case
• Most Likely (M) → Normal case
• Pessimistic (P) → Worst case

👉 Formula (PERT):

Expected Time (TE) = (O + 4M + P) / 6

👉 Example:

• O = 2 days
• M = 4 days
• P = 8 days

TE = (2 + 4×4 + 8) / 6 = (2 + 16 + 8)/6 = 26/6 ≈ 4.33 days

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🔸 5. Bottom-Up Estimation

• Estimate small tasks first, then combine

👉 More accurate but time-consuming

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🔹 5. Units of Measurement

• Hours
• Days
• Weeks

👉 Avoid vague terms like “soon” or “quickly”

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🔹 6. Diagram Description

📌 Activity duration estimation is often shown in:

👉 Gantt Chart

• Bars represent duration of tasks over time

👉 Network Diagram (PERT/CPM)

• Nodes = activities
• Arrows = dependencies
• Duration written on tasks

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🔹 7. Example

Task: Develop login feature

Estimate Type	Time
Optimistic	2 days
Most Likely	3 days
Pessimistic	6 days

👉 Using PERT:

TE = (2 + 4×3 + 6)/6 = (2 + 12 + 6)/6 = 20/6 ≈ 3.33 days

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🔹 8. Important Exam Points

• Duration ≠ Effort 👉 (Effort = total work, Duration = calendar time)

• Use PERT formula for accuracy

• Consider risks and uncertainties

• Always base estimates on data or experience

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🔹 9. Common Mistakes

❌ Ignoring risks ❌ Over-optimistic estimates ❌ Not considering dependencies ❌ Lack of historical data

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🔹 10. Short Summary

• Estimating activity duration = predicting time required for tasks

• Uses techniques like:

  • Expert judgment
  • Analogous
  • Parametric
  • Three-point (PERT)

• Accurate estimation is key for successful scheduling

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🔹 11. Quick Exam Answer (2–3 lines)

Estimating activity duration is the process of predicting the time required to complete a project task. It uses techniques such as expert judgment and PERT, and is essential for creating an effective project schedule.

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🔹 12. Likely Exam Questions

1. Define activity duration estimation.
2. Explain the PERT formula with example.
3. What factors affect activity duration?
4. Differentiate between effort and duration.
5. Describe different estimation techniques.
6. Why is accurate duration estimation important?