A manufacturer produces micron chips for personal computers. From past experience, the production manager believes that 1% of the chips are defective. The company collected a sample of the first 1,000 chips manufactured after 4:00 P.M every other day for a month. The chips were analyzed for defects; then these data were used to construct the p-chart shown here.

a. From a statistical perspective, is a sample size of 1,000 adequate for constructing the p-chart? Explain.
b. Calculate the chart's upper and lower control limits.
c. What does the p-chart suggest about the presence of special causes during the time when the data were collected?
d. Critique the rational subgrouping strategy used by the disk manufacturer.

Transcribed Image Text:

P Chart of DEFECTS UCL D000 Certe oos 0.010 0.005 0.000 Sample Number Proportion