Question

Euro Coins After constructing a control chart for the proportions of defective one-euro coins, it is concluded that the process is within statistical control. Does it follow that almost all of the coins meet the desired specifications? Explain.

Short answer

No, it cannot be concluded that the coins follow the required specifications.

A control chart only examines whether the process mean/process variation is within statistical control. It does not establish any conclusion on whether the goods follow the given specifications.

Step-by-step solution

Given information

A control chart is plotted for the proportions of defective coins. By observing the control chart, it is concluded that the process is under statistical control.

No Information on Process Specifications Using Control Charts

The process's actual behavior and not the desired behaviordeterminesthe upper and lower control boundaries of a control chart for a proportion p.

If a process is concluded to be under control using the control chart, it does not guarantee whether the goods produced satisfy the required specifications.

Thus, it cannot be said that all coins meet the desired specifications.