Question 1

When constructing a u-chart,the standard deviation of each sample varies because the size of the sampling unit varies.

Accepted Answer

In a u-chart, which is used for monitoring the number of defects per unit in a process, the standard deviation varies because it is dependent on the sample size, and in the case of a u-chart, the sample sizes (or the sizes of the sampling units) can vary. This variation in sample size directly affects the calculation of the standard deviation for each sample.

Question 2

If a process is neither capable nor in control,the appropriate first step is to:

Accepted Answer

When a process is neither capable nor in control, the first step is to identify and remove any special causes of variation. This is because it is important to first stabilize the process before attempting to improve its capability. In contrast, removing common causes of variation may not be as effective in improving the process capability, as these are inherent to the process and are not easily eliminated. Redesigning equipment or determining the process capability index should only be done after the special causes of variation have been addressed.

Question 3

Control limits for variables and attributes data utilize different mathematical formulas.

Accepted Answer

Control limits for variables data are based on the Normal distribution and use formulas involving the mean and standard deviation, while control limits for attributes data are based on the binomial distribution and use formulas involving the proportion and sample size.

Question 4

The output of a process is stable and normally distributed.If the process mean equals 23.5,the percentage of output expected to be less than or equal to the mean:

Accepted Answer

A normal distribution is symmetric, meaning that the area under the curve to the left of the mean is equal to the area under the curve to the right of the mean. Therefore, 50% of the output is expected to be less than or equal to the mean value of 23.5.

Question 5

_____ is measured as the amount of error in a measurement in proportion to the total size of the measurement.

Accepted Answer

The answer of _____ is measured as the amount of...

Question 6

Compared to variable measurement,attributes measurement requires _____ to obtain the same amount of statistical information about the quality of the product.

Accepted Answer

Attributes measurement is a form of non-destructive testing that classifies the quality of a product as either conforming or nonconforming to a set of specifications. It requires a larger sample size to obtain the same amount of statistical information because it relies on counting the number of nonconforming units in a sample rather than measuring a continuous variable.

Question 7

In pre-control,which zone covers the nominal specification of a process?

Accepted Answer

The green zone covers the nominal specification of a process in pre-control.

Question 8

In service applications,the term _____ is generally used to describe a nonconformance.

Accepted Answer

In service applications, nonconformance is often referred to as an error. This can refer to an error in the provided service or an error made by the service provider. Neither of the other options - cycle or trend - accurately describes a nonconformance in service applications, and while unit could be used in some contexts, error is a more common term.

Question 9

If the cost of investigating an operation to identify the cause of an apparent out-of-control condition is low,narrower control limits should be selected.

Accepted Answer

If the cost of investigating an operation is low, it makes sense to choose narrower control limits because it implies that the consequences of not detecting an issue could be significant. Therefore, selecting narrower control limits can help detect any apparent out-of-control condition promptly.

Question 10

In determining the method of sampling,samples should be chosen to be as heterogeneous as possible so that each sample reflects the system of common causes or assignable causes that may be present at that point in time.

Accepted Answer

Samples should be chosen to be as homogeneous as possible so that each sample reflects the system of common causes or assignable causes that may be present at that point in time. By minimizing the variability within the sample, it becomes easier to identify the cause of any variation and implement appropriate corrective actions.

Question 11

Control limits for the s-chart are given by: LCLs = B3s and UCLs = B4s,where B3 and B4 are constants.

Accepted Answer

The answer of Control limits for the s-chart are given...

Question 12

If the variation in the process is due to common causes alone,the process is said to be:

Accepted Answer

If the variation in the process is due to common causes alone, the process is said to be in statistical control. This means that the variation in the process is stable and predictable, and can be measured using statistical process control techniques. Out of control refers to a process where the variation is not stable and predictable, and there are special causes of variation present. In pre-control refers to a simpler method of controlling a process that has low capability. Out of capability refers to a process that cannot consistently meet the specification limits.

Question 13

Defects per million opportunities (dpmo)= _____.

Accepted Answer

Defects per million opportunities is calculated by taking the number of defects discovered and dividing it by the total opportunities for error, then multiplying by 1,000,000. This calculation ensures that the number is represented as a whole number and can be compared to industry standards for quality control.

Question 14

Process capability calculations make little sense if the process:

Accepted Answer

Process capability calculations require the process to be in statistical control, meaning that variations in the process are due to common causes and not attributed to special causes.

Question 15

Collecting _____ data is usually easier than collecting _____ data because the assessment can usually be done more quickly by a simple inspection or count.

Accepted Answer

Attribute data is qualitative data that describes the presence or absence of a certain characteristic or attribute, whereas variable data is quantitative data that can vary in magnitude. Collecting attribute data is usually easier than collecting variable data because it can be assessed by a simple inspection or count, without having to measure or quantify anything. Therefore, option C is the best choice.

Question 16

A(n)_____ characterizes the presence or absence of nonconformances in a unit of work.

Accepted Answer

An attribute characterizes the presence or absence of nonconformances in a unit of work. Attributes data are categorical and are often represented by "pass" or "fail" results. Variables refer to data that can be measured and have numerical values, while indicators are tools or instruments used to measure or show something. Errors are mistakes or deviations from desired results.

Question 17

Variable data are _____.

Accepted Answer

Variable data are continuous, meaning they can take on any numerical value within a certain range. For example, the height of a person or the temperature outside are both variable data that can be measured as a continuous value. Discrete data refers to distinct and separate values, while nonrandom and not measurable are not accurate descriptions of variable data.

Question 18

A c-chart is based on the binomial distribution.

Accepted Answer

A c-chart is based on the Poisson distribution, which is used for counting the number of defects per unit of output.

Question 19

A process is said to be out of control when:

Accepted Answer

A process is said to be out of control when special causes are present, which means there are unexpected variations in the process that can cause defects or errors. Common causes, on the other hand, are expected variations that do not warrant any action. The capability of the process and the computation of control limits are not necessarily indicators of whether the process is in control or not.

Question 20

_____ is a study of variation in a measurement system using statistical analysis.

Accepted Answer

A repeatability and reproducibility (R&R) study is a specific type of study that focuses on evaluating the variation in a measurement system through statistical analysis. Metrology study, calibration study, and SPC (Statistical Process Control) study are broader terms that may include a variety of analyses beyond just evaluating variation.

Quiz 8: Measuring and Controlling Quality