There are many tools that have been created in order to perform root cause analysis. Some of these tools are the Pareto chart, failure mode and effects analysis (FMEA), and the fishbone diagram. While all of these tools are useful, the fishbone diagram will be looked at more closely.

The fishbone diagram has few other names such as the cause and effect diagram, 5-Whys, and the why-why diagram. These names are appropriate because this tool seeks to find the reasons why a particular event (the effect) was caused.

To complete the analysis, you should identify the effect and work backwards. With this process you will try to determine the cause. In order to identify the cause of the effect, you will need to ask the question "Why did this effect happen?" Several answers may come up and a list will be created. Once you have your list, you will then ask "Why did this cause happen?" for each item you came up with.

For every cause, the "why" question is asked till no more answers could be generated or till five generations have been completed (hence the 5 -Whys. Due to it,the general shape of this diagram looks similar to a horizontal tree. At the far right the original event(the effect) is listed. Then a horizontal line is drawn towards the left. From the horizontal line,the answers the "why" questions are listed. Then the reasons for those answers are branched off. In most of the cases,the branches are a little bit slanted creating a look of a fishbone.

An example of the 5-why chain for a company which has just lost a customer follows. The company lost its customer because the price was too high. The price was too high because the assembly process took longer than it should have. The assembly took too long because the workers didn't have the correct tools. They didn't have the correct tools because the tools weren't ordered. The tools weren't ordered because upper management was hoping to cut costs for the quarter.

As soon as the basic cause has been discovered, actions can be put in motion to make sure this can be either circumvented, in the case of a negative result, or repeated in the case of a positive one. If the basic cause of a problem isn't correctly recognized, then only the symptoms will be dealt with, not the actual reason for the problem itself. Dealing with situations in this manner can result in higher costs, inferior quality, sluggish delivery or possibly all three.