ISTQB FOUNDATION 4.0 | Tutorial 47 | Test Estimation Techniques | Wide Band Delphi | Extrapolation

Summary

This tutorial delves into test estimation techniques for ISTQB Foundation level certification, focusing on Chapter 5. It explains the importance of test estimation in determining the adequate level of testing needed to achieve project quality objectives. The video outlines two primary estimation methods: Matrix-based, involving calculations and ratios, and Expert-based, relying on team consensus and individual expertise. Techniques such as estimation by ratios, extrapolation, Wideband Delphi, and three-point estimation are discussed, providing a comprehensive guide to test managers for estimating effort, cost, and time in software testing projects.

Takeaways

• 📘 Test estimation is a crucial responsibility of the test manager, aiming to determine the required effort, cost, and time for testing activities within a project lifecycle.
• 🔍 The purpose of test estimation is to answer the question 'how much testing is enough' to achieve the desired quality level or meet project objectives.
• 📈 Estimations are performed early in the project lifecycle, parallel to project planning, and help project managers understand the time needed for testing.
• 📊 Test effort estimation involves predicting the amount of work needed for testing and is based on assumptions, subject to estimation errors.
• 🔢 Small tasks tend to have more accurate estimates than larger ones, suggesting that breaking down large tasks into smaller ones can improve estimation accuracy.
• 📉 Two main types of estimation methods are discussed: Matrix-based estimation and Expert-based estimation, each with its own techniques and approaches.
• 📝 Matrix-based estimation techniques include estimation based on ratios, which uses completed projects as a reference, and extrapolation, which uses ongoing project data to predict future activities.
• 🎲 Expert-based estimation techniques involve people-driven estimates, such as Wideband Delphi, where experts estimate in isolation and reach a consensus through discussion, and Planning Poker, its variant used in Agile development.
• 📊 Three-point estimation (PERT) is an expert-based technique where three estimates (optimistic, most likely, and pessimistic) are calculated to provide a final estimate with a tolerance for error.
• 🤝 The process of reaching a consensus in expert-based techniques involves discussions among experts to reconcile differences in their initial estimates.
• 📚 The tutorial aims to provide clarity on various estimation techniques, emphasizing the importance of understanding these methods for effective test management.

Q & A

What is the main purpose of test estimation in the context of ISTQB Foundation level certification?

The main purpose of test estimation is to predict the amount of test-related work needed to meet the objectives of a test project, helping the test manager to understand how much testing is enough to achieve the desired level of quality or meet project objectives.

Why is it important for a test manager to estimate testing effort, cost, and time?

It is important for a test manager to estimate these factors to plan the testing activities effectively, allocate resources appropriately, and communicate the required time and effort to the project manager and stakeholders.

What does the script suggest about the accuracy of estimations in testing?

The script suggests that estimations in testing are not meant to be absolutely accurate but rather to be as close as possible to the accurate, acknowledging that there will always be some estimation error based on assumptions.

Why are smaller tasks usually estimated more accurately than larger ones?

Smaller tasks are usually estimated more accurately because they are less complex and more manageable, allowing for a clearer understanding of the effort required. Larger tasks can be broken down into smaller ones for better estimation accuracy.

What are the two main categories of estimation techniques discussed in the script?

The two main categories of estimation techniques discussed are Matrix-based estimation and Expert-based estimation.

Can you explain the concept of estimation based on ratios?

Estimation based on ratios involves using an existing or completed project as a reference and applying the same ratios of effort, time, or cost to a new, similar project to estimate the required resources.

How does the extrapolation technique work in the context of Matrix-based estimation?

Extrapolation involves using measurements and data from the current project to predict future activities. It is often used in iterative development cycles to estimate the effort required for upcoming iterations based on the average effort from previous ones.

What is the difference between Wideband Delphi and Planning Poker in the context of Expert-based estimation?

While both are people-driven estimation methods, Wideband Delphi involves experts making individual estimates in isolation and then discussing to reach a consensus, whereas Planning Poker is a group activity where estimates are made using cards with numbers to represent effort size.

What is the three-point estimation technique and how is it calculated?

The three-point estimation technique involves making three estimates: the most optimistic (A), the most likely (M), and the most pessimistic (B). The final estimate (E) is calculated as (A + 4M + B) / 6, and the standard deviation (SD) is calculated as (B - A) / 6.

How does the script suggest using the results of previous projects for estimation purposes?

The script suggests using the ratios of effort, time, or cost from previous projects as a reference to estimate similar aspects of a new project, which can provide a more accurate and realistic estimation.