Ishikawa Diagram

The Ishikawa diagram – also called the fishbone diagram, cause-and-effect diagram or 6M/8M method – is a graphical method for uncovering the causes (more generally: influencing factors) of a problem in a structured way. It was developed by Kaoru Ishikawa, a Japanese organisational theorist in quality management. The diagram is one of the seven basic tools of quality management.

Why “fishbone”?

On the far right is the problem – the head of the fish. The main bones branch off from the spine: the cause categories. The concrete causes hang from them and can be branched out further. The picture forces you to work in a structured way and not to forget any category.

When to use it?

Whenever a problem is tricky: the cause is not obvious, and there may even be several at once. Incidentally, the method can also be used the other way round – to collect ideas for achieving a goal (goal in the head, approaches on the bones).

The 8M – the category cheat sheet

Tip: You do not have to use all the Ms. Man and Method almost always fit; Material and Machine make more sense in production. For other problems simply choose suitable categories of your own (see the examples “Blood samples” and “Online shop”).

Limits of the method

With a very large number of causes the diagram quickly becomes cluttered – in that case show one branch separately. Complex interactions across category boundaries can hardly be depicted; the diagram remains a simplification.

Everything saves itself. Every change is backed up within a few seconds – “Saved” at the top shows that everything is fine. You do not need a Save button; Ctrl+S still saves immediately.

Templates stay unchanged. If you open a template and enter something, the tool automatically creates your own analysis. You change the title directly in the title field at the top; you will find all analyses under “Analyses”.

Undo and redo: The arrows next to the status display revert changes or restore them – also with Ctrl+Z and Ctrl+Y (Mac: ⌘Z and ⇧⌘Z).

History: In addition to continuous saving, the tool keeps earlier versions – when opening, at most every 10 minutes while you work, and whenever you name a version yourself. There you can compare, restore (this too can be undone with Ctrl+Z) or create a version as a new analysis.

Writing: In the text fields you write as in a word processor – with headings, lists, checklists, tables, quotes, arrows and symbols. The toolbar appears while you write; with / you open all commands. While typing, -> turns into →.

Attachments: Photos and files – for example an Excel list from the customer – you simply drag into the text field. They travel along inside the HTML file; photos are scaled down for this. For many or large files there is the ZIP bundle with the “Attachments” folder under “File”.

This HTML file is your document. All analyses, attachments and the history are inside it. Under “File → Save to your own file …” you choose a location once; after that the tool writes every change there automatically (Chrome and Edge). In Firefox and Safari the same command downloads the file – open that file from now on.

In case something goes wrong: The tool continuously stores an interim version in the browser. If the browser crashes, your work is back the next time you open it.