If the capability of this process improves, which one of the following best describes a change that would occur?

When the capability of a process improves, it typically means that the process becomes more efficient and consistent in producing output that meets quality standards. One key aspect of process capability is the variation of the output. If a process is operating at a higher capability, it indicates that the process is better controlled and that the variability in the output has been reduced.

This reduction in variation is often represented by a tighter distribution of the process measurements around the target or mean value. Lower variation means that the outputs of the process are more consistently centered around the desired specifications, leading to a higher percentage of products that meet quality expectations.

In contrast, if process variation were to increase, it would imply that the outputs are becoming less consistent, leading to more outputs falling outside specification limits. Specification limits refer to the predetermined boundaries that determine whether a product meets quality standards; improved capability would not lead to narrower specification limits unless the process definition itself was altered. Similarly, an increase in the amount of product out of spec would contradict the idea of improvement in process capability, as reduced variation would typically result in a decrease in out-of-spec products.

Thus, the most accurate and comprehensive description of what happens when process capability improves is that process variation decreases, leading to more consistent and reliable outputs.