Making a diagram does not necessarily have to be dull and stuffy. Workshopping and putting together a FAST diagram can bring your team together in a way that can almost feel like a game. Read on to find out what a FAST diagram is and how it works.

Overview: What is the Function Analysis System Technique?

FAST is a technique that is used to develop a representation graphically, where the relationships between functions in a product, process, or service can be displayed. This is accomplished by asking the questions “how” and “why”.

3 benefits of the Function Analysis System Technique (FAST)

There are clear benefits to utilizing the Function Analysis System Technique in virtually any industry:

1. Identification

With FAST, you can succinctly identify all of the functions involved in a process.

2. Visualization

The Function Analysis System Technique provides the ability to easily visualize the relationships between all of the functions.

3. Points you to answers

The technique can help answer the “how” and the “why”.

Why is FAST important to understand?

FAST is important to understand for the following reasons:

It is objective and exhaustive

It begins with the expressed needs and shows the ways to answer them as thoroughly as possible.

Clarity of development

It can clearly lay down the basis of a project from its inception through every stage of development.

Common understanding

The technique can provide a common understanding of the product, service, or process amongst the team involved.


The technique can break down the scope of the project as well as the tasks to complete it and how they correspond.

An industry example the of the Function Analysis System Technique

A long-term customer has asked a company to make them a specialized product. There is some disagreement amongst the members of the team as to whether this will be an appropriate use of resources. It is decided that a workshopping session will be held to decide whether creating this specialized product is in the best interest of the team. The team leader opts to present the team with a FAST diagram, with everyone providing input into the functions involved in the product. As a teambuilding exercise, the FAST diagram is a success, and it is determined by consensus that the product is worth making for the long-term customer.

4 best practices when thinking about Function Analysis System Technique

If you are going to build a Function Analysis System Technique diagram, here are some practices to utilize in order to do it well:

1. Start with good functional analysis

This means listing all of the functions of your product, service, or process. From here, you then prioritize them. Identify which ones are the primary functions, the basic functions, the secondary ones, and so on.

2. “How” and “why”

For each function that you identify, you should ask “how” it is accomplished and put the answer on the right. You should also ask “why” this function should be undergone and write the answer on the left.

3. Add, adjust, and eliminate

Next, you should identify any functions that may be redundant or missing. This is also when you can adjust the priority of functions.

4. Spot relationships between functions

Identify functions that happen concurrently or that rely on one another. Also, note if one function triggers another. Write “when” these things occur, underneath.

Frequently Asked Questions (FAQ) about the Function Analysis System Technique

Who is involved in creating a FAST diagram?

The FAST diagram is generally created while workshopping and is led by someone that has experience in its preparation. What is inputted into the diagram comes from the participants of the workshop.

Is there a “correct” FAST diagram?

There is no set correct way to do a FAST diagram. The key is to provide the data in a way that is most beneficial to the group, and that should be the determining factor in how the model is presented.

What kinds of things can be mapped with FAST?

You can use FAST for the graphic modelization of goals, procedures, processes, projects, products, systems, and much more. They are always broken down into function terms.

Function Analysis System Technique works

Utilizing this technique can help with the clarification of intent, achieve consensus amongst a group, and even broaden viewpoints. It also minimizes emotion within the group through depersonalization. Beyond all that, it has been shown to save money and aid in decision-making. Adding FAST to your repertoire of tools can help take your business further, just as it has for many in business for over fifty years.

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