Certified Production & Operations Manager (POM) Practice Exam

What does a c-chart indicate regarding the quality of a product?

1. Change in the total process time

2. Change in the number of defects per unit

3. Change in customer satisfaction

4. Change in supplier performance

The correct answer is: Change in the number of defects per unit

A c-chart, or count chart, is specifically used in statistical quality control to monitor the count of defects in a process over time. It is designed to track the number of defects per unit within a specific sample size, making it particularly useful in instances where the defects can be counted as discrete items rather than measured on a continuous scale. When utilizing a c-chart, practitioners can identify trends, shifts, or unexpected variations in the defect count, which directly indicates the quality of the product being produced. A rising count on a c-chart could signal a deterioration in product quality, prompting further investigation or corrective action. This focus on defect counts is what makes option B the correct answer, as it directly connects the function of a c-chart to monitoring quality in terms of defects per unit. The other options focus on different aspects not directly related to the defect count, such as overall process time, customer satisfaction levels, and supplier performance, which are not what a c-chart is designed to measure. Thus, the strength of the c-chart lies in its ability to provide a clear view of defects per unit, which is critical for maintaining and improving quality standards in production.