The Center Line (P-Bar) for a P-Chart Is 0

Multiple Choice

The center line (p-bar) for a p-chart is 0.50 with an ULC = 0.65 and a LCL = 0.35. The results of the next eight sample means are 0.45, 0.60, 0.39, 0.44, 0.48, 0.58, 0.54, and 0.64. Which of the following is the best action to take?

A) Collect eight additional samples and then decide.
B) Wait and collect more data by increasing the sample size.
C) Investigate assignable causes because four observations are above the center line.
D) Investigate assignable causes because there is a bad trend (run) .