Exam 3: Statistical Quality Control

If the points plotted on a control chart display a pattern,it is called a run.

Attribute qualitative)control charts are used to monitor descriptive characteristics of the output of a process.

The process capability ratio measures the specification limits over the control limits.

A company randomly selects 100 light bulbs every day for 40 days from its production process.If 600 defective light bulbs are found in the sampled bulbs then the estimate for the process average defective would be

With a c-chart,the sample size is small and often contains only one item.

What is a c-chart and when is it used?

A c-chart monitors the number of defects in small samples.

In some cases,the xbar-chart is used without the R-chart because the within sample variation is not of concern.

When special cause variation is detected it is normally eliminated by increasing the number of standard deviations Z value)used to calculate the control limits.

Which of the following control charts are based on sample sizes as small as one?

Briefly discuss attribute and qualitative variable quality measures.

Statistical process control is based on a philosophy of inspection as opposed to prevention.

In some cases,the xbar-chart is used without an R-chart because there is no variation between the samples.

Some companies that strive to provide extremely high quality use Z=6 six sigma)vs.Z=3 three sigma)when constructing control limits.

Unique or special cause variation reflects the random variation associated with the output of a process.

Information from an R-chart can be used to construct the control limits for an xbar-chart.

The goal of statistical process control is to ensure that the control limits and specifications limits for a process always remain the same.

Which of the following control charts is used to control the variation between samples?

One advantage of using a pattern test is that special cause variations may be identified before any points are plotted outside the control limits.

Control chart sample sizes are becoming smaller because it is easier to detect a pattern with Excel or other data analysis software.