Chapter 14: Q10CQQ (page 654)

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

Short Answer

Expert verified

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.