This p-chart shows a process that goes out of control. At about the 12th or 13th sample, the probability of a non-conforming item more than doubles. Click on the graph to generate a new set of 25 samples of 100 each. Can you see the signs that the process is out of control in the second half of the samples? Sometimes it is difficult.

.  In these p-chart examples, which of the following is most accurate?

     a. The process is not in control because there are several points that exceed the upper limit line.

     b. The process is not in control because the first half of the points are generally below the center line, while the second half          are generally above the center line.

     c. The process is not in control because the points tend to trend lower from left to right.

     d. The process is not in control because several points are less than the lower limit line.

 

2.  In these p-chart examples, which of the following behaviors indicates of a out-of-control process?

     a. The points appear to be randomly above and below the center line.

     b. Several points in a consecutive sequence are above the center line.

     c. Several points exceed the limit lines.

     d. The points are trending lower from left to right.

 

Fraction Nonconforming 0.14 0.12 0.10 0.08- 0.06 0.04 0.02- 0.00 1-60 www. 15 20 20 10 Sample Number 25