computer science

GQM

GQM is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand GQM rather than just read about it. In short: GQM (goal, question, metric) is an established goal-oriented approach to software metrics to improve and measure software quality. History GQM has been promoted by Victor Basili of the University of Maryland, College Park and the Software Engineering Laboratory at the NASA Goddard Space Flight Center after supervising a Ph.D. thesis by Dr.

GQM — main illustration — GQM — illustration

Key takeaways

GQM belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect GQM to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of GQM from memory before moving on to harder problems.

Reference excerpt

GQM (goal, question, metric) is an established goal-oriented approach to software metrics to improve and measure software quality.

History GQM has been promoted by Victor Basili of the University of Maryland, College Park and the Software Engineering Laboratory at the NASA Goddard Space Flight Center after supervising a Ph.D. thesis by Dr. David M. Weiss. Dr. Weiss' work was inspired by the work of Albert Endres at IBM Germany.

Method GQM defines a measurement model on three levels:

1. Conceptual level (Goal) A goal is defined for an object, for a variety of reasons, with respect to various models of quality, from various points of view and relative to a particular environment. 2. Operational level (Question) A set of questions is used to define models of the object of study and then focuses on that object to characterize the assessment or achievement of a specific goal. 3. Quantitative level (Metric) A set of metrics, based on the models, is associated with every question in order to answer it in a measurable way.

GQM stepwise Another interpretation of the procedure is:

Planning Definition Data collection Interpretation

Sub-steps Sub-steps are needed for each phases. To complete the definition phase, an eleven-step procedure is proposed:

Define measurement goals Review or produce software process models Conduct GQM interviews Define questions and hypotheses Review questions and hypotheses Define metrics Check metrics on consistency and completeness Produce GQM plan Produce measurement plan Produce analysis plan Review plans

Recent developments The GQM+Strategies approach was developed by Victor Basili and a group of researchers from the Fraunhofer Society. It is based on the Goal Question Metric paradigm and adds the capability to create measurement programs that ensure alignment between business goals and strategies, software-specific goals, and measurement goals. Novel application of GQM towards business data are described. Specifically in the software engineering areas of Quality assurance and Testing, GQM is used.

Further reading Victor R. Basili's contributions to software quality (IEEE Software, 2006) Solingen/Berghout: The Goal/Question/Metric Method: A Practical Guide for Quality Improvement of Software Development (PDF, 2015)

Illustrations

Worked examples

Example 1 — a first encounter with GQM

Start with the simplest possible case. Write down what GQM claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to GQM before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about GQM ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of GQM

In research: GQM appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses GQM in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: GQM is common in secondary-school and first-year university syllabi. It links to neighbouring topics Software metrics, Software quality, so understanding it makes those chapters shorter.
In everyday life: Look for GQM outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study GQM in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what GQM means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain GQM out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is GQM in simple terms?

GQM (goal, question, metric) is an established goal-oriented approach to software metrics to improve and measure software quality. History GQM has been promoted by Victor Basili of the University of Maryland, College Park and the Software Engineering Laboratory at the NASA Goddard Space Flight Cent…

Why does GQM matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study GQM?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on GQM.

GQM