Using the cause-and-effect diagram.
The Ishikawa diagram (cause-and-effect diagram), also known as a fishbone diagram, is a guide to solving complex problems that take a long time to resolve. The fishbone diagram enables a structured approach and is ideal for analyzing situations in a team or individually.
The Ishikawa diagram (cause-and-effect diagram or fishbone diagram) is named after one of the fathers of the Quality Circle movement, Kaoru Ishikawa. The Ishikawa diagram is a visualization of a problem-solving process in which the primary causes of a problem are sought. The starting point is a horizontal arrow pointing to the right, at the tip of which is the problem formulated as concisely as possible (e.g.: "high error rate during welding process").
Slanted cause arrows (the bones) now aim at this arrow from above and below. These main arrows are in turn pointed at by horizontal arrows, where the causes of the problems found are entered. By alternating between the oblique and horizontal arrows, you can now search for deeper and deeper causes. The rule of thumb is the technique of the five "whys". It is assumed that you have to ask "why" up to five times before you get to the actual root of the problem.
The fishbone diagram can be used to illustrate several tasks.
If you only have to solve one problem at a time, a fishbone diagram is not necessary. However, as you usually have to solve several problems at the same time, it is easy to lose track. If you make a separate fish plan for each problem, you can get an overview of all the tasks at hand each day. After reviewing the fish plans, you can set priorities and decide what needs to be done today in order to make progress on the individual problems. The tool makes it easy to identify and analyze the possible causes and effects of a problem area.
The Ishikawa diagram examines four to six influencing variables:
People
- All causes arising from lack of experience, skills, knowledge, personal behavior, dislike, attitude to work, etc.
- All causes that may have arisen from company policies or strategic/operational management decisions.
- All causes that may have arisen from internally defined work processes, organizational structures, service instructions, control and approval procedures.
- All causes that could have arisen from the materials and supplied parts used.
- All causes that may have arisen due to external influences such as customer behavior, legal regulations, competition situations, labor market situations, etc.
- Look at the focused problem description
- Identify possible causes and name the "bones" (categories)
- Develop and arrange the "sub-bones" (individual causes)
- Scrutinize the individual causes to find secondary causes
- Evaluate the particularly relevant causes
- Agree on measures to solve the problem
