Fishbone Diagrams – Why And How

The identification of the reason for an event increases the chance that the event can be caused or prevented in the future. The process of finding the fundamental reason why some event or defect occurred is called Root Cause Analysis.

There are a lot of tools that have been made for root cause analysis to function. Several tools are the Pareto chart, the failure mode and effects analysis (also known as FMEA), as well as the fishbone diagram. Although every one of these tools are worthwhile, the fishbone diagram will be examined more intensely.

Introducing the Ishikawa Diagram

The fishbone chart has several other titles like the cause and effect charts, 5-Whys, and the double-why chart. These titles fit well since this tool functions as a method to discover the reason why a certain event occurred.

By working from the end after figuring out the effect is the universal algorithm for coming up with a hypothesis. Usually, this is the incident or problem someone is trying to identify. Determining cause and effect is after that. If you ask yourself “What is causing this?”, you can come up with many different responses and you should compose those in catalog form. Upon the determination of the answer, you ask yourself again.

Five Whys Root Cause Analysis

The 5-Whys are 5 generated why questions asked for each cause until no further answers can be generated. The 5-whys when put into a diagram will resemble a horizontal tree. The effect or the original event (tree) will be on the far right of the tree. Then horizontal lines are drawn to the left to create a “branch” in which the “why” questions are listed from. The answers are then branched off, on a slight angle, from the “why” question branches, which can resemble a fishbone look.

The following is an example of the 5-why chain for a company that just lost a patron. The company lost its customer simply because the price was too high. The high price is a result of the delayed assembly process taking longer than it should have. The assembly took longer because the workers had incorrect tools. The workers don’t have the right tools because they were never ordered. The tools were never ordered in an effort by upper management to cut costs for the quarter.

After the root cause is uncovered, measures may be taken either to either guarantee that the root cause can be prevented in the future if the end result was a negative one, or else that it occurs again if there was a positive result. Only the symptoms of the problem get treated, as opposed to the cause, if the core of the problem is not correctly identified. Practices such as these could bring on extra costs, slower delivery, lesser quality, or all three.