CHAPTER 16 TRUE FALSE
A c-chart monitors the number of conforming items.
False
A process is considered to be in control when all common and special causes have been eliminated
FALSE
An X-bar-chart is always analyzed first because the control limits in the R-chart depend on the mean ( ) of the data.
FALSE
Both the p-chart and the c-chart use variable data
FALSE
If no common causes affect the output of a process, the process is in control.
False
A system governed only by common causes is called a stable system
TRUE
When the range of process variation is larger than the design specifications, the process capability index will be less than 1
TRUE
A discrete metric is one that is calculated from data that are counted.
True
A process might be off-center and still show an acceptable value of process capability index, Cp.
True
An R-chart is always analyzed before an x-bar chart.
True
Points outside the control limits signify an out-of-control situation in a process.
True
A c-chart is used to monitor the fraction nonconforming, whereas a p-chart monitors the number of nonconformances per unit
FALSE
As long as no points are outside of the control limits in a control chart, the process would be considered to be in control.
FALSE
Collecting continuous data is usually easier than collecting discrete data
FALSE
Common cause variation generally accounts for about 10 to 15% of all variation within a process
FALSE
It generally costs more to correct an error or defect at the design stage than after it has reached the customer
FALSE
It is not necessary to have a process in control when establishing control limits
FALSE
Quality at the source" focuses on supplier quality at the beginning of a value chain
FALSE
Quality control focuses on the design of a good or service to ensure meeting customer expectations
FALSE
Quality control of front-office operations in services can effectively use many of the same techniques that are applied in manufacturing
FALSE
The value of Cpk is the average of the lower and upper capability indexes; that is, Cpk = (Cpl + Cpu)/2.
FALSE
To account for the process centering, a two-sided capability index is often used
FALSE
With good management, all variability of output from any goods- or service-producing process can be eliminated
FALSE
A large sample size is desirable to keep the cost associated with sampling low.
False
In-process control is typically performed by top management.
False
It is both desirable and economical to use large sample data on frequent basis.
False
Keeping common cause variation from occurring is the essence of statistical quality control.
False
Quality at the source means that the ultimate quality of a finished good cannot be any better than the quality of the raw material used.
False
R-charts and x-bar charts are used with discrete data.
False
Special cause variation is the result of complex interactions of variation in materials, tools, machines, information, workers, and the environment.
False
Statistical process control (SPC) is more useful for processes that operate at a high sigma level than a low sigma level.
False
The 1:10:100 Rule states that the value of a good increases exponentially as it progresses from supplier to manufacturer to customer.
False
A key element of a control system is the ability to measure performance and compare it to a performance standard.
TRUE
If process quality approaches six sigma levels, then standard types of control charts are not useful
TRUE
If the mean in the range chart shifts down significantly, it indicates that the variation in the process has decreased.
TRUE
In developing process control charts, if special causes are present, they are not representative of the true state of statistical control, and the calculations of the center line and control limits will be biased
TRUE
In manufacturing, quality control is generally applied at the receiving stage from suppliers, during various production processes, and at the finished goods stage
TRUE
In-process quality control is typically performed by the employees who run the processes
TRUE
Larger sample sizes allow smaller changes in process characteristics to be detected with higher probability
TRUE
Over-adjusting a process that is in control will usually increase the variation in the output
TRUE
Poor quality that might result from a broken tool or an employee who is ill would be an example of special cause variation
TRUE
Process capability quantifies the variation that results from common causes.
TRUE
Special cause variation tends to be easily detectable using statistical methods
TRUE
The goal of statistical process control (SPC) is to help identify and eliminate unwanted causes of variation
TRUE
The lower the rate of defects, the higher the sample size should be in p-charts
TRUE
A process that is in control does not need any changes or adjustments.
True
All control charts are similar in structure, but the specific formulas used to compute control limits for them differ.
True
If supplier documentation is done properly, incoming inspection can be completely eliminated.
True
Process capability is important to both product designers and process owners.
True
The two key issues while designing control charts are sample size and sampling frequency.
True
Whenever an unusual pattern in a control chart is identified, the process should be stopped until the problem has been identified and corrected.
True
