What type of control chart is appropriate when there may be multiple defects per item?

• A. R-chart
• B. p-chart
• C. c-chart
• D. x-bar chart

Answer: (C)

A c-chart is specifically designed to monitor the count of defects in a process where there can be multiple defects per item. This type of control chart is useful in quality control because it helps industries track variations in the number of defects over time. The c-chart is based on a Poisson distribution, which is appropriate for counting occurrences that can happen in a given area or sample.

In contrast, the other types of charts serve different purposes. An R-chart is used to monitor the variability of subgroups of a measurement, focusing on the range of values rather than counting defects. A p-chart, on the other hand, is suitable for situations where you are dealing with the proportion of defective items in a sample, not the number of defects per item. Lastly, an x-bar chart is employed to monitor the mean of a process rather than counting defects, making it inappropriate for situations involving multiple defects per item. Thus, the c-chart is the correct choice for tracking multiple defects effectively.