Exam 13: Statistical Quality Control

Measurement by attributes means taking a sample, measuring the attribute in question, and determining the level of quality in the population from which the sample was drawn.

You are developing an X-bar chart based on sample means.You know the standard deviation of the sample means is 4, the desired confidence level is 99 percent, and the average of the sample means is 20.Which of the following is your LCL?

The capability index (Cpk) calculates the percentage of items being produced within specifications.

You are going to develop an R-chart based on range statistics, and you are using a sample size of 9 for your charting purposes.Which of the following is the lower control limit D3 factor for the chart?

Sampling plans are generally displayed graphically through the use of operating characteristic (OC) curves.

You want to determine the control lines for a p-chart for quality control purposes.If the desired confidence level is 99 percent, which of the following values for "z" would you use in computing the UCL and LCL?

It is impossible to have zero variability in production processes.

In variables sampling, the actual measurements of the variable observed are used regardless of whether the unit is good or bad.

AQL stands for accepting questionable lots in production quality management.

The producer's risk associated with rejecting a high-quality lot is denoted in acceptance sampling with the Greek letter beta.

If the fraction defective is 0.12 based on a sample size of 16, the standard deviation used in the p-chart is about 0.08.

The probability associated with accepting a low-quality lot is denoted in acceptance sampling with the Greek letter alpha.

You want to determine the control lines for a p-chart for quality control purposes.If the total number of defects from all samples is 560, the number of samples is 70, and the sample size is 80, which of the following would be the standard deviation used in developing the control lines?

You want to determine the control lines for a p-chart for quality control purposes.If the total number of defects from all samples is 2,500, the number of samples is 100, and the sample size is 50, which of the following would be the standard deviation used in developing the control lines?

If the fraction defective is 0.4 based on a sample size of 100, the standard deviation used in the p-chart is about 0.10.

The capability index is used to gauge economic changes in service systems.

The value for "z" used in quality control charts is based on the degree of confidence you want to have in the resulting UCL and LCL values.

You have just used the capability index (Cpk) formulas to compute the two values "min [1.5, 1]." Which of the following is the interpretation of these numbers?

For which of the following should we use an X-bar chart based on sample means to monitor process quality?

In acceptance sampling, the value for the acceptance number (c) is determined by the interaction of the acceptable quality level (AQL), the lot tolerance percent defective (LTPD), the probability of rejecting a high-quality lot (alpha), and the probability of accepting a low-quality lot (beta).