SQL MCQ Set 1
1. The assumption that links normality to the control charts is ___________
a) The underlying distribution of the quality characteristic is normal
b) The normal mean will be equal to the process mean
c) The normal distribution is not the correct distribution for all the quality charcteristic
d) Every distribution is a part of normal distribution.
Answer
Answer: a [Reason:] There is an assumption that links the normality to the control charts in the development of the performance properties of x bar and R charts; that is, the underlying distribution of the quality characteristic is normal.
2. The probability of not detecting “an in-control shift” of the mean of the process is said to be the _____
a) α- Risk
b) β- Risk
c) γ- Risk
d) δ- Risk
Answer
Answer: b [Reason:] If the mean of a process shifts from one value to another value with process being in-control, and shift is not detected on the control chart, the probability of this event is called the β- Risk.
3. If the sample size is 7 and the Average run length is 122 for a process, what will be the expected number of the individual units sampled?
a) 850
b) 854
c) 867
d) 844
Answer
Answer: b [Reason:] We know,
I=nARL
Putting n=7 and ARL=122, we get, I = 854.
4. If β- risk of any process is 0.75, what will be the ARL for that process
a) 4
b) 1.33
c) 0.86
d) 2
Answer
Answer: a [Reason:] ARL is given by,
Putting β=0.75, we get ARL=4.
5. Slope of OC curve for x bar chart will _____ when sample size is increased.
a) Decrease
b) Increase
c) Remain same
d) Decrease then increase
Answer
Answer: b [Reason:] The OC curve is the curve between the β- risk against the magnitude of the shift in mean expressed in std. deviation units for different sample size. Its slope decreases as sample size is increased.
6. If the probability of one point plotting out of control limits of a X bar control charts is 0.0143, what will be its expected number of individual units sampled with subgroup size 8?
a) 559
b) 544
c) 530
d) 580
Answer
Answer: a [Reason:] We know, ARL=1⁄α and I=nARL. From question we get, α=0.0143 and n=8.
Using this data we get; I≈559.
7. A mixture pattern in the control chart points is exhibited when ____ occurs.
a) Operator fatigue
b) Change of raw materials
c) Continuous wear of tool
d) Adjustments too often responding to random variation
Answer
Answer: d [Reason:] When the “Over-control” occurs, i.e. the operator adjusts the processes very frequently and recurrently, the random pattern of the process data vanishes and a mixed pattern is obtained.
8. If the means for sample 1 to 4 for a process are, 12.67, 22.32, 14.53, 12.11; what value will be the center line of x chart indicating?
a) 15.2
b) 15.4
c) 14.8
d) 14.9
Answer
Answer: b [Reason:] The center line of the x chart, indicates the mean of all means of samples; i.e.,
9. A permanent change in the sample size is made only because of cost or because has exhibited good stability and fewer resources are allocated for process monitoring.
a) True
b) False
Answer
Answer: a [Reason:] The permanent change in sample size is not a frequent activity. So it is done because of some major reasons like cost or extraordinary good performance of process on control chart.
10. Which of these should be plotted on the x bar chart?
a) Counts
b) Defects
c) Problems Solved
d) Measurements
Answer
Answer: d [Reason:] Counts, defects and problems solved are all quantities which increase in a discrete amount. Measurements increase in a continuous way. Only Continuous quantities are plotted on the x bar chart.
SQL MCQ Set 2
1. Once a set of reliable control limits is obtained, we use the control chart for monitoring future production. This is called _____
a) Phase I control chart usage
b) Phase II control chart usage
c) Phase III control chart usage
d) Phase IV control chart usage
Answer
Answer: b [Reason:] The use of reliable control limits to monitor the future production from a process, is generally mentioned as the Phase II application of control chart while, setting the trial control limits to monitor the process is called the Phase I application.
2. When R chart is out of control, we _____
a) Eliminate the out-of-control points and recalculate the control limits
b) Take one more sample and recalculate the control limits
c) Eliminate the out-of-control points and the nearest two points, and recalculate the control limits
d) Take no action
Answer
Answer: a [Reason:] When R chart is out of control, we often eliminate the out-of-control points and recompute a revised value of R bar. This will help us recalculate the control limits.
3. When the upper and lower natural tolerance limits are equal to the upper and lower specification limits, the process capability ratio, cp is ___
a) Greater than 1
b) 0
c) Less than 1
d) Equal to 1
Answer
Answer: d [Reason:] When the natural tolerance limits are having a equal value to the specification limits for a quality characteristic, the process capability ratio, cp is having a value equal to 1.
4. X bar chart monitors _____
a) Between-sample variability
b) Within-sample variability
c) Neither between-sample nor within-sample variability
d) Both between-sample variability and within-sample variability
Answer
Answer: a [Reason:] A x chart is only used to monitor the variability of a whole process over time. It does not detect variability within a sample but variability between all the samples of a process output.
5. Unlike x chart, which measures between-sample variability only, an R chart is used to monitor ____
a) Both between-sample variability and within-sample variability
b) Within-sample variability only
c) Between-sample variability only
d) Neither between-sample variability nor within-sample variability
Answer
Answer: b [Reason:] A R chart is a chart which uses sample ranges to calculate its center line and control charts. So it only measures within-sample variability, i.e. the instantaneous variability at a given time.
6. When using standard values of process mean and standard deviation, the equation of UCL for a x chart is given as, UCL= μ+Aσ
What is the value of A here?
a) 6/√n
b) 3/√n
c) √n/6
d) √n/3
Answer
Answer: b [Reason:] When using the standard values of process mean and standard deviation, A in the equation of UCL for x chart is given by
7. For standard values of mean and standard deviation used, what does the center line of the R chart represent?
a) R bar
b) d2 σ
c) D2 σ
d) d2 R
Answer
Answer: b [Reason:] For the standard values of mean and standard deviation used, the center line for a R chart is determined by the following formula,d2 σ.
8. The control limits obtained by specifying the type I error level for the test, are called _____
a) Probability limits
b) Trial limits
c) Error limits
d) Unreliable limits
Answer
Answer: a [Reason:] It is possible to define the control limits for a control chart by specifying the type I error level. The limits obtained by this way, are called the Probability limits for the control chart.
9. Which chart should be interpreted first when both, x chart,and R chart are indicating a non-random behavior?
a) x chart
b) R chart
c) X and R chart
d) Trial Limits
Answer
Answer: b [Reason:] It is a property of control charts for x bar and R, that if they both indicate non-random behavior, and if R chart is interpreted first to delete the assignable causes in it, it will automatically delete assignable causes in x bar chart.
10. Which of these is a cause of trend patterns on a control chart?
a) Gradual wearing out of some critical process component
b) Operator fatigue
c) Environmental changes
d) Over-control
Answer
Answer: a [Reason:] A trend or continuous movement in one direction on a control chart is generally caused by gradual wearing out of some critical process component like deterioration of a tool.
11. Shift in process level can be seen on the control charts when _____
a) Operator fatigue occurs
b) Temperature changes
c) Over-control of process
d) New workers introduction
Answer
Answer: d [Reason:] Shift in the process level is a phenomenon seen on the control chart patterns. It occurs when there is introduction of new workers, or there is a change of methods.
12. Stratification is defined as ___
a) Tendency for the points to cluster artificially around the center line
b) Shift in the process level
c) Continuous movement of points in one direction
d) When the points fall near or slightly outside the control limits
Answer
Answer: a [Reason:] Stratification is defined as the tendency of the points on a control chart, to cluster around the center line of the control chart. It occurs very frequently while applying control charts to a process.
13. Stratification of points on a control chart indicates _____ of natural variability of the process.
a) Lack
b) Increase
c) Constancy
d) Randomness
Answer
Answer: a [Reason:] Stratification makes the points in a control chart to be plotted around the control chart center line; which indicates that the randomness is gone and there is a lack in natural variability of the process.
14. Never attempt to interpret the x chart when the R chart indicates the out of control condition.
a) True
b) False
Answer
Answer: a [Reason:] It is easy to eliminate the assignable causes in the x chart by eliminating the assignable causes in the R chart. This implies, if there is indication of out-of-control condition of process from the R chart and x chart; then first, R chart must be interpreted.
15. The 3 sigma limits on x bar control charts imply that the type I error probability is _____
a) 0.0012
b) 0.0072
c) 0.0027
d) 0.0037
Answer
Answer: c [Reason:] The 3 sigma control limits on x bar control charts will imply that the type I error probability is 0.0027 or 0.27%. It will give 2700 defectives per million units of production.
SQL MCQ Set 3
1. DMAIC stands for ______
a) Do-Measure-Act-Implement-Check
b) Define-Measure-Act-Implement-Control
c) Define-Measure-Analyze-Improve-Control
d) Do-Measure-Analyze-Improve-Control
Answer
Answer: c [Reason:] DMAIC is a problem solving process. It is a collection of 5 steps. D stands for Define, M stands for Measure, A stands for Analyze, I stands for Improve and C stands for control.
2. What DMAIC process does is, to _______
a) Manufacture any product
b) Define specification limits for a product
c) Solve root cause of quality and process problems
d) Define quality system standards
Answer
Answer: c [Reason:] DMAIC is a problem solving tool. Hence, its main objective is to find root causes of problems in a process, which create variability. It attempts to remove those root origins.
3. Which of these is not a part of Define step of DMAIC process?
a) Verify and gain approval for final solutions
b) Define critical customer requirements
c) Establish project charter and build team
d) Document process
Answer
Answer: a [Reason:] Define step of DMAIC, consists of identifying or validating the improvement opportunity, knowing customer requirements, mapping process, and establishing project charter.
4. DMAIC is often associated with ______
a) Six-sigma activities
b) Kaizen board
c) 5-s
d) Acceptance sampling
Answer
Answer: a [Reason:] DMAIC is often associated with six-sigma activities. The main objective of this is to give the maximum output with good quality. Almost all six-sigma implementation use DMAIC PSP for project management and completion.
5. PSP is expanded as ____
a) Problem Solving Process
b) Product safeguarding process
c) Product Sampling Process
d) Project Settling Procedure
Answer
Answer: a [Reason:] PSP is expanded as Problem Solving Process. There are many types of PSP’s available. DMAIC PSP is one of them.
6. The Cause and Defect Diagram is a part of _____ step of DMAIC process.
a) Define
b) Analyze
c) Control
d) Measure
Answer
Answer: d [Reason:] The cause and defect diagram is an diagram which shows defects in a product, and the corresponding cause for it. This is counted in the Measure step of DMAIC.
7. Tollgate reviews are presented to managers and “owner” of a process, __________ in the six-sigma organizations.
a) The project champions and the black belts not working directly on the project
b) Industrial engineering team
c) Quality control manager
d) Developers of the factory
Answer
Answer: a [Reason:] Tollgate reviews are the reviews of a report developed by the project team. In a six sigma organization, the project champion and the black belts also review this report, besides the manager and the owner.
8. Improve step of DMAIC can also be changed by Design step in the case of some processes.
a) True
b) False
Answer
Answer: a [Reason:] When the original process is operating very badly, or if there is a new product or service is required, then the Improvement step of DMAIC process actually becomes Design step.
9. DFSS refers to _____
a) Development of Six-Sigma
b) Design for Six-Sigma
c) Define for Six-Sigma
d) Development for Six-Sigma
Answer
Answer: b [Reason:] For a six-sigma organization, when it is determined that a new product is required, the improve step in DMAIC becomes Design step. This is sometimes called, Design for Six-Sigma.
10. Tollgate reviews are done _______
a) Before each step of DMAIC
b) After DMAIC process ending
c) Before the whole DMAIC process
d) After each step of DMAIC process
Answer
Answer: d [Reason:] Tollgate reviews are done after each step of DMAIC process. They contain a review by the manager and owner, of a report of the step which is developed by the project team. This offers evaluation of the work of the team.
11. Process capability tests are a part of _____ step of DMAIC process.
a) Define
b) Improvement
c) Measure
d) Control
Answer
Answer: c [Reason:] Measure step contains the evaluation of the current state of the production process.
12. A DMAIC process is implemented on a process only when ______
a) There are signs of potential breakthrough
b) It is estimated that quality of products will decrease in near future.
c) Exceptionally bad quality review of a product
d) When the project impact of DMAIC is estimated low
Answer
Answer: a [Reason:] DMAIC process is put into practice only when there are chances of improvement in the final quality of product/service. This improvement or potential change is measured on the basis of financial improvement.
13. Projects with high potential negative impact are _____
a) Most desirable
b) Least desirable
c) Having highest risk
d) Have a low risk
Answer
Answer: c [Reason:] Projects which have a chance of positive impact on the final product quality are most suitable for DMAIC application. But if the impact is predicted negative, they become the least desirable of all projects.
14. DMAIC can be carried out without tollgate reviews.
a) True
b) False
Answer
Answer: b [Reason:] DMAIC is a problem solving process carried out by project team. If this team makes an mistake in any one step, and it is not reviewed by experts like manager and the owner, it can result in negative impact on the process.
15. In SIPOC diagram, P stands for _______
a) Process
b) Product
c) Progress
d) Profit
Answer
Answer: a [Reason:] SIPOC is a high level map of a process where SIPOC stands for Supplier, Input, Process, Output, and Customer. This is an important part of Define step of the DMAIC process.
SQL MCQ Set 4
1. In the design of experiments, the ____ variables are adjusted first.
a) Output controllable
b) Output uncontrollable
c) Input uncontrollable
d) Input controllable
Answer
Answer: d [Reason:] In the design of experiments, the value of input controllable variables is varied to find the desired output quality of a process.
2. Which of these can be varied?
a) Input Controllable variables
b) Input uncontrollable variables
c) Output controllable variables
d) Output uncontrollable variables
Answer
Answer: a [Reason:] Only the input controllable variables can be varied. This is because all the other variables are uncontrollable like input uncontrollable variables etc.
3. Which of the following is not done in the designing of experiments?
a) Varying the input variables (controllable)
b) Observation of the output
c) Making a relationship between input and output
d) Process control
Answer
Answer: d [Reason:] In the design of experiments, the controllable inputs of a process are varied, and the output of the process is observed simultaneously, then a relationship between the inputs and the outputs, is made.
4. Which of these is not a function of designing of experiments?
a) To find the set of process variables influential on output
b) To determine the optimum level of the variables
c) To estimate maximum output possible with optimum value of variables
d) To eliminate some uncontrollable inputs
Answer
Answer: d [Reason:] Designed experiments are helpful in finding, which set of process variables is influential on the output, and at what levels these variables should be held to optimize the process performance.
5. Which of these is the easiest method for finding the sources of variability?
a) Designed Experiments
b) p-charts
c) n-charts
d) Acceptance sampling
Answer
Answer: a [Reason:] Designed experiments are useful in determining the optimum level of the process variables for a better process performance, so we can find the sources of variability simultaneously.
6. Which of these is not a method to judge the process capability?
a) Control charts
b) Attributes data
c) Acceptance sampling
d) Designed experiments
Answer
Answer: b [Reason:] Process capability can be determined by the usage of either of control charts, or attributes data or designed experiments. The process capability ratios, histogram and the probability plots also can be used.
7. DPU is ____
a) Decrement per unit
b) Defects per unit
c) Design per unit
d) Decimals per unit
Answer
Answer: b [Reason:] The term “DPU” is used in the determination of process capability by using the attribute data. Here, DPU stands for Defects per unit.
8. DPMO stands for ____
a) Defects per million opportunities
b) Decrement per minute opportunity
c) Defects per minute opportunity
d) Designation per million opportunities
Answer
Answer: a [Reason:] DPMO represents the defects per million opportunities. It takes the complexity of an unit into account when calculating the process capability.
9. Which of these is the correct formula to calculate DPMO which uses the number of opportunities?
Answer
Answer: d [Reason:] DPMO is calculated by using the following formula,
As this formula contains the number of opportunities, it takes the number of times that an error can be occurred. So it is much accurate.
10. If there are 85 defects in the lot containing 150 units, what is the value of DPU?
a) 0.45
b) 0.57
c) 0.89
d) 1.52
Answer
Answer: b [Reason:] DPU is calculated by using the following formula,
By calculating the DPU, we get, DPU=0.57.
11. If the DPMO for a sample containing 45 units is 0.237. If the total number of defects is 32, what will be the number of opportunities?
a) 3
b) 1
c) 6
d) 7
Answer
Answer: a [Reason:] DPMO is calculated using the formula,
Putting the values, we get, the number of opportunities= 3.
12. PPM defectives can be a measure of the process capability. Although an equivalent sigma level can also be used.
a) True
b) False
Answer
Answer: a [Reason:] As a particular sigma level shows a particular amount of defectives, e.g. 2700 ppm is equivalent to 3-sigma process; an equivalent sigma level can be used instead of using the ppm defectives as a measure of the process capability.
13. DPU can be evaluated only when, the variable data is available.
a) True
b) False
Answer
Answer: b [Reason:] As DPU suggests the defects found per unit of the product, which is an attribute data, we do not need the variable data to calculate the DPU.
SQL MCQ Set 5
1. Which one of these tells explicitly about the potential capability of the process?
a) Histogram
b) Probability plots
c) PCRs
d) Control charts
Answer
Answer: d [Reason:] Histogram, process capability ratios and the probability plots all can only summarize the performance of process. They don’t necessarily display the process potential capability.
2. Which one of these addresses the issue of statistical control?
a) Design of process experiments
b) Probability plots
c) Control charts
d) Histogram
Answer
Answer: c [Reason:] The probability plots, histogram and PCRs are just tools to summarize the process performance. They don’t address the issue of statistical control. Control charts only, are capable of doing that.
3. Which one these show that, if the systematic pattern in process output is eliminated, it would produce a lesser variability in the quality characteristic?
a) Probability plots
b) Control Charts
c) Histogram
d) PCRs
Answer
Answer: b [Reason:] As control charts address the issue of statistical control of the process, they insure that there must be random patterns in the process output, so that variability is reduced.
4. Which one of these is primary technique of the process capability analysis?
a) Histogram
b) Process capability ratios
c) Probability plots
d) Control charts
Answer
Answer: d [Reason:] As control charts are main technique to reduce variability, by taking the statistical control into consideration, control charts are regarded as the primary technique of the process capability analysis.
5. Which chart should be used, if possible?
a) x & R Charts
b) u Charts
c) p Charts
d) c Charts
Answer
Answer: a [Reason:] As x & R charts are the variable control charts and the others are attribute control charts, taking the fact “variable charts give better information than the others” into consideration, x & R charts are favored over the others.
6. Which one of these charts doesn’t need the specification of the quality characteristic?
a) x & R Charts
b) p-charts
c) c-charts
d) u-charts
Answer
Answer: a [Reason:] The variable control charts don’t need the specification of the quality characteristic, so x & R charts don’t need the specifications of the quality characteristic.
7. Which one of these helps us to find both instantaneous and the variability across time variability?
a) p-charts
b) np-charts
c) x & R Charts
d) c-charts
Answer
Answer: c [Reason:] The charts for x & R are quite useful in determination of the instantaneous and the variable across time variability of a quality characteristic.
8. What is the second name of instantaneous variability?
a) Long term variability
b) Short term variability
c) Long distance variability
d) Variability across time
Answer
Answer: b [Reason:] Instantaneous variability is the variability for a small tenure of process operation. It is also known as the short term variability.
9. Which one of these is similar to the long-term variability?
a) Instantaneous variability
b) Variability across time
c) Large variability
d) Large distance variability
Answer
Answer: b [Reason:] The variability across time phrase is also known as the long term variability, as this phrase is used for the variability calculated for a big interval of time.
10. Which control charts will be useful if the process output data for the process capability study are collected in different time periods?
a) x & R Charts
b) p-charts
c) c-charts
d) u-charts
Answer
Answer: a [Reason:] As variable control charts are capable of determining the process capability of both types, i.e. the instantaneous variability, and the variability across time, they are used, when the data for process capability analysis is collected in different shifts.
11. If the Cpl of a safety-related parameter, is 0.69, what can we say about the process capability?
a) Process is capable
b) Process is not capable
c) Process is capable but will become not-capable in sooner time
d) Process is not-capable but will become capable in sooner time
Answer
Answer: b [Reason:] For a safety-related parameter, we know that the one-sided process capability ratio must be greater than, 1.50 for an existing process, or 1.67 for a new process. So the above mentioned process capability is inadequate.
12. Which one of these can be used as the monitoring device to show the effect of changes in the process on process performance?
a) Control charts
b) Designed experiments
c) Histogram
d) Probability plots
Answer
Answer: a [Reason:] Control charts give the time to time data about the process output in a visual display. So we can use them as a monitoring device to show the effect of changes in the process, on process performance.
13. If Cpu=1.82 for strength quality characteristic for a new process, can we use the process?
a) Process is capable
b) Process is not capable
c) Process is capable but will improve in sooner time
d) Process is not capable but will improve in sooner time
Answer
Answer: a [Reason:] As strength is a safety parameter, the minimum value for Cpu for it for a new process is 1.67. So we can use the above mentioned new process.
14. p-charts can be used rather than using the x & R charts, in the case of variable time spans of data collection.
a) True
b) False
Answer
Answer: b [Reason:] As variable charts are more capable of finding the process capability to analyze both instantaneous variability and the variability across time, x & R charts are more used instead of p-charts.
15. Histograms explain the process statistical control better than the control charts.
a) True
b) False
Answer
Answer: b [Reason:] As control charts are real time representation of the quality characteristic of process output according to time, they explain the process statistical control better than any other method.
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