Certified Production & Operations Manager (POM) Practice Exam

Which control chart is best suited for tracking the number of defects per unit for a production line?

1. p-chart

2. c-chart

3. U-chart

4. x-bar chart

The correct answer is: c-chart

The c-chart is specifically designed to monitor the number of defects in a fixed sample size. It is particularly useful when measuring attributes that are countable and non-negative, such as defects per unit. This type of chart is effective in quality control processes, allowing organizations to maintain the standard of their production lines by identifying trends, shifts, or variations in defect rates over time. In contrast, the p-chart is utilized for monitoring the proportion of defective items in a sample rather than counting the number of defects per unit. The U-chart is suitable for tracking the number of defects per unit while allowing for varying sample sizes, making it less applicable when the sample size is consistent. The x-bar chart focuses on the mean of continuous data rather than the count of defects, which does not align with the need to track defect counts. Therefore, the c-chart stands out as the most appropriate choice for this specific tracking purpose.