Question 1

Process control is concerned with monitoring quality after the product or service has been produced.

Accepted Answer

Process control is concerned with managing and controlling the process of production to ensure that product quality is maintained throughout the manufacturing process, not just after production is complete.

Question 2

It is impossible to have zero variability in production processes.

Accepted Answer

Variability is inherent in any production process because it involves numerous factors, such as human error, machinery wear and tear, and raw material variations. Even with strict quality control measures, there may still be some degree of variability present. Therefore, zero variability in a production process is practically impossible to achieve.

Question 3

If the fraction defective is 0.12 based on a sample size of 16,the standard deviation used in the "p" chart is about 0.08.

Accepted Answer

The standard deviation used in the "p" chart is calculated as √(p(1-p)/n), where p is the proportion of defects in the sample and n is the sample size. Plugging in the values given, we get √(0.12(1-0.12)/16) = 0.0808, which is approximately 0.08. Therefore, the statement is true.

Question 4

To obtain a 99.7 percent confidence level in a "p" chart we would use a value of 3 for "z".

Accepted Answer

This is true. A 99.7 percent confidence level corresponds to a three-sigma level, which corresponds to a z-value of 3.

Question 5

An example of assignable variation in a production system may be that a machine is not adjusted properly.

Accepted Answer

Assignable variation refers to specific, identifiable causes of variability in a production system that can be traced back to a particular source, such as a machine not being adjusted properly. In contrast, common variation refers to random or natural sources of variability that cannot be attributed to a specific cause.

Question 6

Statistical process control involves testing random samples of output from a process to determine whether the process is producing items within a preselected range.

Accepted Answer

Statistical process control involves monitoring and testing samples of output from a process to determine whether the process is producing items within a preselected range of acceptable quality. By analyzing these samples, managers can identify whether the process is operating normally or whether there are deviations that may require corrective action.

Question 7

"p chart" has upper and lower control limits expressed as lines on the chart.As long as the sample values fall between these two lines there is no need to investigate process behavior.

Accepted Answer

The answer of "p chart" has upper and lower control...

Question 8

Genichi Taguchi's view of the cost of quality is that variance is a discontinuous function.

Accepted Answer

Genichi Taguchi's view of the cost of quality is that variance from the target value increases quality costs continuously, not discontinuously, as it moves away from the target.

Question 9

Measurement by attributes means taking a sample,measuring the attribute in question and determining the level of quality in the population from which the sample was drawn.

Accepted Answer

The answer of Measurement by attributes means taking a sample,measuring...

Question 10

Variation that is inherent in a production process itself is called common variation.

Accepted Answer

Common variation is the variation that is present in every production process due to factors such as differences in materials, machines, operators, and environment. It is also referred to as natural variation or random variation.

Question 11

In acceptance sampling,the value for the acceptance number (c)is determined by the interaction of the acceptable quality level (AQL),the lot tolerance percent defective (LTPD),the probability of rejecting a high quality lot (alpha),and the probability of accepting a low quality lot (beta).

Accepted Answer

The answer of In acceptance sampling,the value for the acceptance...

Question 12

Attributes are those quality characteristics that are classified as either conforming or not conforming to specification.

Accepted Answer

This statement accurately describes the definition of attributes in quality control.

Question 13

AQL stands for accepting questionable lots in production quality management.

Accepted Answer

AQL stands for Acceptable Quality Level, a statistical measurement of the maximum number of defective goods considered acceptable in a sample size during an inspection.

Question 14

If the fraction defective is 0.4 based on a sample size of 100,the standard deviation used in the "p" chart is about 0.10.

Accepted Answer

The standard deviation used in a p-chart is calculated using the formula $\sqrt{\frac{p(1-p)}{n}}$, where $p$ is the fraction defective and $n$ is the sample size. Substituting $p = 0.4$ and $n = 100$ gives $\sqrt{\frac{0.4(1-0.4)}{100}} = \sqrt{\frac{0.4(0.6)}{100}} = \sqrt{\frac{0.24}{100}} = \sqrt{0.0024} = 0.049$, which is approximately 0.05, not 0.10.

Question 15

The value for "z" used in quality control charts is based on the degree of confidence you want to have in the resulting UCL and LCL values.

Accepted Answer

This is true. The value for "z" (or the number of standard deviations from the mean) is determined based on the desired level of confidence, which in turn affects the resulting upper control limit (UCL) and lower control limit (LCL) values in a quality control chart. The higher the degree of confidence desired, the larger the value of "z" used to calculate the control limits.

Question 16

Acceptance sampling is performed on goods that already exist to determine what percentage of items conforms to specifications.

Accepted Answer

Acceptance sampling is a statistical quality control measure used to determine the quality level of a batch of goods that have already been produced. It involves randomly selecting a sample of items from the batch and testing them to see if they conform to pre-determined specifications or standards. Based on the results of the testing, one can determine the quality level of the entire batch and decide whether to accept or reject it.

Question 17

The "p chart" is only useful for sampling that deals with continuous variables.

Accepted Answer

The "p chart" is used to monitor the proportion of nonconforming items in a sample, regardless of whether the variable is continuous or discrete.

Question 18

The capability index is used to gauge economic changes in service systems.

Accepted Answer

The capability index is not used to gauge economic changes in service systems. It is a statistical measure used to assess a process's ability to meet customer requirements, particularly in the manufacturing industry.

Question 19

Variation that is inherent in a production process itself is called assignable variation.

Accepted Answer

Variation that is inherent in a production process itself is called common cause variation, not assignable variation. Assignable variation is caused by specific factors that can be identified and eliminated.

Question 20

In acceptance sampling,the number of units in the sample (n)is determined by the interaction of the acceptable quality level (AQL),the lot tolerance percent defective (LTPD),the probability of rejecting a high quality lot (alpha),and the probability of accepting a low quality lot (beta).

Accepted Answer

In acceptance sampling, the sample size (n) is determined by the AQL, LTPD, alpha, and beta. These factors interact to determine the appropriate sample size.

Quiz 10: Quality Management and Six-Sigma Supply Chain Processes and Analytics