You want to determine the upper control line for a p-chart for quality control purposes. You take several samples of a size of 100 items in your production process. From the samples you determine the fraction defective is 0.05 and the standard deviation is 0.02. If the desired confidence level is 99.7 percent, which of the following is the resulting UCL value for the line?
A) 0.39
B) 0.11
C) 0.06
D) 0.05
E) None of these

Question

Quizplus · Accepted Answer

The UCL for a p-chart is calculated as p + z * σ, where p is the fraction defective (0.05), z is the z-value for the desired confidence level (3 for 99.7%), and σ is the standard deviation (0.02). Thus, UCL = 0.05 + 3 * 0.02 = 0.11.

You Want to Determine the Upper Control Line for a P-Chart