Home Chapter 7 Quiz

# Quiz

This activity contains 15 questions.

## Which of the following statements about variables is true?

 Variables control charts contain more information than attributes charts and are more sensitive statistically. Variables control charts are less likely than attributes charts to be affected by operation of special causes masking effects. Variables control charts are more effective than attributes charts at detecting out of control states. All of the answers are correct.

## When using variables control charts, one should read:

 both charts simultaneously because neither chart can stand alone. the inherent variability chart first to get a sense of process stability. the central tendency chart first to develop an overview of the process. None of the choices are correct.

## If a process is in a state of statistical control, the variability between subgroups will be:

 less than the variability within subgroups because the inherent variability is being controlled. small, but greater than the variability within subgroups since the process average is changing. equal to the variability within subgroups, that is equal to the inherent variability of the process. None of the choices are correct.

## Give the preferred method for detecting shifts in process average.

 the random continuous sampling method selection of consecutive units close together in time The preferred method is dependent upon the application employed. Both methods are equal.

## The ratio of the range of a sample (from a normal distribution) to the standard deviation of the distribution is:

 used to estimate from . a random variable whose mean and standard deviation are a function of the size of the sample used. called the relative range. All of the choices are correct.

## As the sample size increases, the best measure of variability is:

 None of the choices is correct. the range, because the probability of observing an extreme score in a sample increases with increasing sample size. Both choices are correct and subject to researcher preference. the standard deviation, because it makes use of all the information available and reduces the effect of a single extreme score on the variability estimate.

Three process and sampling schemes are listed below.

I. Product is produced in a batch process. The well-mixed, unsettled batch is sampled at the end of the run.
II. Product is produced continuously at a high flow rate and is sampled each hour.
III. Product is produced continuously at a low flow rate and is sampled minimally to avoid product loss.

Choose the scheme that would require individual values charts.

 I, II, and III I and III I and II II only

## The ____________ method estimates process variability by considering differences between consecutive observations.

 random sampling moving range relative range variables control

## If trends are present in the data the moving range method tends to ________________ and result in control limits that are too ______________.

 overestimate; narrow underestimate; wide overestimate; wide underestimate; narrow

## The assumption of normal data distribution is most important in the use of:

 S charts. charts R charts. X charts.

## The statistic used in exponentially weighted moving average charts is:

 . . . .

## Another term for the target value is the:

 nominal value. individual value. specification limit. tolerance limit.

## The natural tolerance limits of a process are:

 used to express the moving range of a process. equal to the spread represented by the upper and lower control limits. always greater than the specified tolerance limits. All of the answers are correct.