The Psychology of Quality and More

A Toolbook for Quality Improvement and Problem Solving (contents)

Cause-Effect Diagram: Examples

The Quality Toolbook > Cause-Effect Diagram > Examples

When to use it | How to understand it | Example | How to use it | Practical variations

<-- Previous | Next -->

Example

The managing director of a weighing machine company received a number of irate letters, complaining of slow service and a constantly engaged telephone. Rather surprised, he asked his support and marketing managers to look into it. With two other people, they first defined the key symptom as 'lack of responsiveness to customers' and then met to brainstorm possible causes, using a Cause-Effect Diagram, as illustrated.

They used the 'Four Ms' (Manpower, Methods, Machines and Materials) as primary cause areas, and then added secondary cause areas before adding actual causes, thus helping to ensure that all possible causes were considered. Causes common to several areas were flagged with capital letters, and key causes to verify and address were circled.

On further investigation, they found that service visits were not well organized; engineers just picked up a pile of calls and did them in order. They consequently set up regions by engineer and sorted calls; this significantly reduced traveling time and increased service turnaround time. They also improved the telephone system and recommended a review of suppliers' quality procedures.

Fig. 1. Example Cause-Effect Diagram

Other examples

• A sales team, working to increase the number of customers putting the company on their shortlist for major purchases, identifies through a survey that the key problem is that the customers perceive the company as a producer of poor quality goods. They use a Cause-Effect Diagram to brainstorm possible causes of this.
• A pig farmer gets swine fever in her stock. To help ensure it never recurs, she uses a Cause-Effect Diagram to identify possible causes of the infection, and then checks if they can happen and implements preventive action to ensure none can happen in future.
• A wood turner notices that his chisels sometimes become blunt earlier than usual. He uses a Cause-Effect Diagram to identify potential causes. Checking up on these, he finds that this happens after working with oak. Consequently, he resharpens the chisels after turning each oak piece.

<-- Previous | Next -->