Question

Examine the following p-chart for defective calculator batteries and briefly describe the action that should be taken.a

Short answer

Upon observing the given p-chart, there appears to be a downward trend in the proportion of defective batteries. Thus, the manufacturer needs to identify the cause of this trend and ensure that it is retained.

Step-by-step solution

Given information

A p-chart is plotted for the proportion of defective batteries.

Determine the procedure of identifying when the statistical process is out of control 

When a statistical process shows one of the following features, then it is said to be out of control:

• It shows visiblly different patterns, trends, or cycles.
• At least one point exceeds the upper control limit, and at least one point falls below the lower control limit.
• Run of 8 Rule: Shows at least eight points above or below the centerline in a row.

Interpret the p-chart

A p-chart is plotted for the proportion of defective batteries.

It can be observed that the points seem to fall a downward trend.

Thus, the process is not within statistical control.

But, since there is a downward trend, the proportion of defectives is decreasing.

Therefore, the manufacture should identify the cause of the trend and should ensure that it is maintained as it will lead to a substantial increase in the production of non-defective batteries.