Exam 3: Statistical Process Control

Control charts visually show when a process is not within statistical control limits.

The range measures the variation within samples versus the variation between samples.

The popularity of Excel and other data analysis software has been a major factor in the increased use of statistical process control.

A process capability ratio greater than one shows that a process is capable of producing output within its specification limits.

A process capability ratio greater than one shows that a process is capable of producing output within its specification limits.

Easy Tax is a service company that prepares tax returns. An outside auditor has examined 20 samples each containing one completed tax return. Consider a service process that completes tax returns. An auditor has taken 20 samples of samples containing one completed tax return. The total number of defects observed over the 20 samples is 200. The LCL for the control chart constructed using three sigma is

The basic purpose of control charts include(s)

Special cause (nonrandom) variation in a process is more likely to be detected with

An R-chart monitors the robustness of a process.

Employee training in statistical process control is a fundamental principle in total quality management programs.

Which of the following is NOT not a characteristic of a control chart?

Consider a service process such as a fast food drive through window. The target for a customer's waiting time is 3.0 minutes. A manager observes the process and randomly collects a sample of four waiting times each hour over a 12 hour period. The sum of the average waiting time for each of the 12 samples is 35.4. The sum of the range for each of the 12 samples is 18.0. The LCL for the process control chart reporting variability between the sample means is

Excel can be used to increase the efficiency and accuracy of determining the process capability ratio and the process capability index.

A process capability ratio reflects the number of (Z) sigmas included in the range between the upper and lower control limits.

Easy Tax is a service company that prepares tax returns. An outside auditor has examined 20 samples each containing one completed tax return. Consider a service process that completes tax returns. An auditor has taken 20 samples each containing one completed tax return. The total number of defects observed over the 20 samples is 200. The UCL for the control chart constructed using three sigma is

It is possible to have low variation within samples while at the same time having high variation between sample means.

Consider a production process that produces tires. A quality engineer has taken 15 samples, each containing 200 tires. The total number of defective tires over the 15 samples is 340. The UCL for the control chart constructed using two sigma is

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.

Marble Inc. makes countertops from a variety of high-end materials. To monitor the quality of its production processes the company randomly selects one countertop and counts the number of blemishes. The results for ten samples are shown below: Given the sample information above, the LCL using sigma = 3 for this process would be

A variable measure classifies while an attribute measure quantifies.