Cause and Effect (Fishbone) Diagram

Cause and effect diagrams, also called Fishbones, are an excellent tool from the Quality Management process. Do not allow the amazing simplicity fool you. You need pencil and paper or a whiteboard if you are working in a group. Team creativity will give you best results.

I have drawn a fishbone freehand, so as not to daunt you with pretty graphics. To start with, set down the problem to be solved, then draw the basic fishbone. You may have as many obvious causes as you like, but you will probably find that there are only a few main ones. so put them in boxes.


You can label the causes

  • Machine,
  • Method,
  • Materials,
  • Measurement,
  • Man, or
  • Mother Nature (Environment), for example.

An alternative would be

  • Equipment,
  • Process,
  • People,
  • Materials,
  • Environment, and
  • Management.

In less of a production-oriented situation you could use

  • Price,
  • Promotion,
  • People,
  • Processes,
  • Place,
  • Policies,
  • Product/Service.

You then brainstorm sub-causes and even sub-causes on sub-causes, and your diagram will get to look more and more like a fish skeleton. Do not hold back from the wildest speculations about causes. You can always eliminate them later.

The applications include working on

  • identifying areas for data collection
  • dwindling sales
  • product returns
  • a website that fails to attract business
  • a problem/issue to determine the root cause
  • reasons why a process is having difficulties, problems, or breakdowns
  • a process not performing properly or producing the desired results
  • and many more.

My experience is using fishbones is that quite often you find you have picked the wrong problem to work on. For example, if you are working on poor sales, it may turn out that the real problem is that the product is wrong. On the other hand, you may have asked enough ‘whys’ to realize that you should be working on one of the sub-causes because that it is the real root cause.

Do not be deterred from doing ‘fishbones on fishbones’.

A Free Computer Program for Fishboning

Above all have fun and don’t lose heart. It may take a while to get the hang of it, but it really works.

An excellent and simple piece of software that you can download for free will enable you to produce fishbones very quickly, The results are also neater and prettier than the ones you would draw by hand, probably.

Called XMind, the program also does mind maps and several other tools, so it’s well worth having.

Here is a Fishbone Diagram I dashed off as an example. It took three minutes. You can see how much easier it is to follow than my hand-drawn example above.

Lack of Sales