Also known as the Ishikawa Diagram or the Fishbone Diagram for Process Failure, this method encourages the investigation to follow a structured process of identifying contributing factors and risks. The technique uses a diagram-based approach for thinking through all of the possible causes of a problem.

It can be summarized in the following steps and on the corresponding diagram below:
1. Identification of the problem - what has occurred to imply risk (what has gone wrong)?
2. Identification of the factors that could contribute to causing the problem (systems? equipment? personnel? external factors? etc.)
3. Identify possible causes for each factor
The method permits to analyse the process and decide on further actions to test the different potential causes:  (data analysis? survey? interview? Research?)
Figure 2. Example of a problem: HTLVI/II test has a positive result but it was not alerted. The transplant coordinator finds out about the reactive test once lung, liver and one kidney have been transplanted. Example of how to use Ishikawa diagram