Exam 25: Process Capability and Spc

Quality control charts usually have a central line and upper and lower control limit lines.Which of the following are reasons that the process being monitored with the chart should be investigated?

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?

Which of the following should we use an "R" chart to monitor process quality?

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?

You want to determine the lower control line for a "p" chart for quality control purposes.You take several samples of a size of 50 items in your production process.From the samples you determine the fraction defective is 0.006 and the standard deviation is 0.001.If the desired confidence level is 99.7 percent,which of the following is the resulting LCL value for the line?

Standard practice in statistical process control for variables is to set control limits so that 95 percent of the sample means will fall within the UCL and the LCL.

Lots are defined as low quality when the percentage of defective units is greater than what?

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.

Variation that is inherent in a production process itself is called common variation.

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 0.01.If the desired confidence level is 99.7 percent,which of the following is the resulting UCL value for the line?

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 want to develop a three-sigma "R" chart.You know the average range is 5 based on several samples of size 10.Which of the following is the resulting UCL?

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

It is impossible to have zero variability in production processes.

Process control is concerned with monitoring quality after the product or service has been produced.