Question

A. Process capability (acceptance sampling) is:

B. A process is out of control/ or in control when:

C. When does productivity increase/ decrease?

D. What action should be taken if a plotted value falls below the lower control limit on a process control chart?

E. What are some implicit/ explicit components of a service delivery system?

F. Each day for two workweeks (10 days total), George weighs x bags from that day’s production. If the average of the means is y oz. and the average range is z oz., what is the lower control limit/ center line/ upper control limit for an x-bar chart for this process?

Answer 1

A. Process capability is defined as a statistical measure of the inherent process variability of a given characteristic. A capability estimate is typically obtained at the start and end of the study to figure out the level of improvement in a quality improvement initiative.

B. A process is said to out of control when one or more data points fall beyond the upper or lower control limits. Also, if seven consecutive data points are either increasing or decreasing, then also the process is said to be out of control. Alternatively, if the data points fall between the upper and the lower control limits, the process is said to be in control.

C. Productivity is Output/Input. The productivity increases if the output is increased with the same level of input or if the output is maintained with a lower level of input. Similarly, if the output decreases with the same level of input or it remains constant even with higher levels of input, the productivity is said to be decreasing.

D. If a plotted value falls below the lower control limit, it signifies a special cause that is worse than the results from the common causes. This special cause then should be identified and remove from the process.