IASSC LSSGB EXAM 2022/2023 Questions and Answers

If the chance that any one of five telephone lines is busy at any instant is 0.01, then what is the probability that all the lines are busy? A. (0.01)^4 B. (0.01)^5 C. (0.01)^6 D. (0.01)^10 - ANSWER B. (0.01)^5 N = 5, p = 0.01, x = 5 Apply Standard formula for Binomial Distribution. Thus, option b is the correct answer. Who should complete the control phase after the successful completion and implementation of the first four phases of DMAIC? A. The green belt alone; the project has been successfully completed. B. The process owner alone; it is his responsibility to take the project from here. C. The process owner and the Green Belt together should complete the control phase. D. The complete team is the most desirable option. - ANSWER D. The complete team is the most desirable option. The control phase should be completed by the entire team. Control is not an insignificant phase of the DMAIC process. The green belt or the process owner alone may not have the ability and knowledge to structure the last control step. So option d is correct. To increase the power of the experiments, what is the best choice in the hands of a Six Sigma team? A. Increase Sample Size B. Reduce Sample Size C. Reduce Significance level D. All of the above - ANSWER A. Increase Sample Size Options b and c are not serious considerations, and thus option d can be ruled out. Conceptually, increase in sample size increases the possible accuracy of the experiment, and thus an increase in power. So, option a is the correct answer. Hypothesis testing is usually done to: A. Statistically validate if a sample mean belongs to the population B. Statistically validate if means of two groups are the same or if they are significantly different C. Statistically validate if variances of two groups are the same or if they are different. D. All of the above - ANSWER D. All of the above Statistically validate if a sample mean does belong to the population, find if means of two groups are the same or if they are significantly different, and validate if variances of two groups are the same or if they are different. Option d is the correct answer. What is the concept behind PDCA? A. The Deming/Shewhart cycle B. Process flow C. Continuous improvement D. Satisfying suppliers - ANSWER C. Continuous Improvement The key question phrase is "concept behind." Option b is inappropriate and does not fit the question. Option a would be correct if the question requested another name for PDCA. Answer option d could be one of the number of potential positive outcomes of this activity. However, the concept behind and objective of PDCA is that of continuous improvement. What are the six experiments called while performing one experiment with five repetitions? A. Randomization B. Replications C. Planned grouping D. Sequential - ANSWER B. Replications Repeated trials or replications are often conducted to estimate the pure trial-to-trial experimental error so that lack of fit may be evaluated. Randomization frees an experiment from the environment and other biases. Sequential experiments are conducted one after another, not all at the same time. Adjustments may be made in the experimentation based upon the knowledge obtained. Almost any DOE contains planned grouping. So answer option b is correct. Which type of chart is used for small shifts in variation? A. Xbar B. p C. c D. CUSUM - ANSWER D. CUSUM The other charts are traditional control charts that are designed to identify significant shifts in process variation, while the CUSUM chart is designed to show small variation shifts What are the distinct types of variation that are noted down in control charts? A.Special and assignable B. Random and chance C. Chance and assignable D. Normal and random - ANSWER C. Chance and assignable Chance and assignable are the two varieties of variation. Chance variation is also referred to as normal or random (among others). Assignable variation is also called special or non-normal. So option c is correct. Which of the following is an advantage of the production of a product in large lots? A. Machine efficiencies B. Customer delivery lead times C. Product transportation D. Product quality - ANSWER A. Machine efficiencies According to the proponents of lean manufacturing and continuous flow, options b, c, and d are all disadvantages. For large lot processing delivery lead times increases, transportation of products increases, and products have more potentiall for damage. Option a is generally recognized as the main advantage of large batch runs that may be more than offset by the disadvantages. So option a is the correct choice. A sample is to a statistic as a population value is to a: A. Sample B. Unit C. Parameter D. Measurement - ANSWER C. Parameter A statistic is derived from a sample. A parameter is derived from a population. So option c is correct. A calculation for reproducibility results in a value of 0 (zero), while repeatability yields a positive number. Without any other considerations, what conclusion can be made regarding the reproducibility result? A. The number of distinct categories is small compared to the appraiser variation. B. Operator influence in the measurement is the main cause of variation. C. Repeat the calculations; no conclusion can be determined without a reproducibility value. D. A reproducibility of zero means there is no operator effect on this measurement. - ANSWER D. A reproducibility of zero means there is no operator effect on this measurement. It is possible to have a reproducibility result of zero when studying automated equipment. Sometimes the appraiser only places a part in an instrument and an automatic reading is recorded in a database. There is no appraiser or operator effect in this kind of measurement, therefore, reproducibility is zero. So option d is correct. Historically, the number of flaws in the finish of surface has an average of 0.45. What is the probability of a randomly selected item having more than one defect in the surface finish? A. 0.0755 B. 0.2869 C. 0.6376 D. 0.3624 - ANSWER A. 0.0755 The Poisson distribution is used to model rates. The probability of exactly "r" events occurring can be computed using the Poisson distribution shown below. Entering values as r = 0 and myu value = 0.45 in the required equation gives the probability of exactly zero defects as 0.6376. Entering values as r = 1 and myu value = 0.45 in the same equation gives the probability of exactly 1 defect as 0.2869. The probability of less than 2 defects is 0.6376 + 0.2869 = 0.9245. Thus, the probability of more than 1 defect is 1 - 0.9245 = 0.0755. So answer choice a is correct. Why are scatter diagrams are useful in problem-solving? A. They display the significant few. B. They eliminate the trivial many. C. They show relationships between variables. D. They highlight assignable causes. - ANSWER C. They show relationships between variables. This question requests a positive response. Options a and b describe the Pareto diagram. Option d is one advantage of control charts (perhaps histograms as well). A scatter diagram depicts the relationship between variables. Specifically, an input variable may have an effect on an output variable. So answer option c is correct. The advantage of using the modern designed method of experimentation, rather than the classical OFAT, is that: A. Everything is held constant except the factor under investigation. B. Experimental error is recognized but need not be stated in quantitative terms. C. Fewer terms and measurements are needed for valid and useful information. D. The sequence of measurement is often assumed to have no effect. - ANSWER C. Fewer terms and measurements are needed for valid and useful information. The key to this question is the meaning of the word 'classical'. To most authors, this term refers to varying one factor at a time (OFAT) while holding all other factors constant. Although this approach may work for very simple problems, it causes havoc with moderately complex systems. The fixed factors do vary, which can waste time, effort, and money. This traditional approach can yield invalid or inconclusive results. Modern design experimentation (including fractional factorials, improved three factor designs, and Latin square logic) squeeze a large amount of valid information from a few trials. Option c is correct. What does ANOVA stands for? A. Analysis of Variance B. Analysis of Variables C. Accuracy of Variance D. Analysis and Validation - ANSWER A. Analysis of Variance Which of these quality tools would NOT be expected to be used during the results confirmation stage of a problem solution ? A. Flow chart B. Pareto diagram C. Histogram D. Control chart - ANSWER A. Flow Chart Note that a negative response is requested. The results confirmation stage uses performance data collection and analysis tools such as check sheets, Pareto diagrams, histograms, and control charts. The flow chart is normally used earlier in the problem-solving process, often to help define the problem. Answer a is the suitable choice. If 6 consecutive samples were taken from a process and precisely measured, you can still expect differences. What type of variation would be the most difficult one to determine? A. Lot-to-lot variation B. Piece-to-piece variation C. Inherent process variation D. Error of measurement - ANSWER A. Lot-to-lot variation The small sample size would make it impossible to give a high level of confidence in the results. However, inherent process variation, piece-to-piece variation, and measurement error are obtainable. Lot-to-lot variation would not be detectable unless carefully planned for (which is not indicated in the question). So option a is correct. Which of the following inference tests does NOT require the knowledge of a test or population variation? A. t test B. Paired t test C. z test D. Chi-square test - ANSWER D. Chi-square test Note that a negative response is requested. All of the above require population or sample variance (or standard deviation) except the chi-square test (with sup6 2 unknown). Option d is correct. Which of the following is the LEAST likely candidate to assist in the problem definition stage of Six Sigma? A. CTQ trees B. Pareto analysis C. Product yield data D. Control charts - ANSWER D. Control charts Note that a negative response is requested. Items like CTQ trees, Pareto, yield data, customer feedback, and so on are useful for project definition. Control charts occur much later in the DMAIC cycle. So answer d is the correct choice. What is the name of the condition if you are running a 7-4 fractional experiment? You know factors A, B, C, D, and E are independent of each other, but you suspect factors F and G are not independent. You conducted a small sub-experiment and discovered a high correlation between factors F and G. A. Collinearity B. Confounded C. Correlation D. Covariates - ANSWER A. Collinearity Having two variables that are highly correlated in the experimental model will make it difficult or impossible to detect which factor really affects the response. This condition is called collinearity. The correct answer is option a. Which of the techniques used in DOE helps you in eliminating errors due to nuisance factors? A. Replication B. Blocking C. Randomization D. Coding - ANSWER B. Blocking By creating blocks in an experiment, you can eliminate the errors due to nuisance factors and thus option b is the correct answer. If P(A) is 0.6 and P(B) is 0.5 and the probability of either event happening is 0.85, what is the probability of both the events occurring? A. 0.25 B. 0.3 C. 0.35 D. 0.4 - ANSWER A. 0.25 0.85 = P(A) + P(B) - P(A&B) = 0.6 + 0.5-0.85 = 0.25. Thus, option a is the correct answer. A process has high variability and an off-centered mean. What is the first action the team needs to take? A. Center the mean B. Reduce Variations C. Increase the specifications D. None of the above - ANSWER A. Center the mean For this process, centering the mean will bring a lot of the non-conforming possibilities within the specification limits. Option a is the answer. What is the use of Scatter Diagrams A.Control the process B. Display the order of tasks or events C. Display correlation D. Identify root causes - ANSWER C. Display correlation Control charts usually do the process controlling. A display of tasks or events may be accomplished with a flow chart or checklist. Cause-and-effect diagrams can help identify root causes. Scatter diagrams are used to display correlation. So option c is correct. Five samples are drawn out of a population of 200, with each sample being of size 5. The sample means are 2, 2.5, 3, 2.6, and 4. What is the sample mean? A. 2.8 B. 3 C. 3.2 D. 3.4 - ANSWER A. 2.8 According to CLT, the sample mean is the mean of all the sample means. Taking an average of all the sample means, the answer is 2.82 which is close to 2.8. Option a is correct. In IT sector, time and effort spent in testing the software, fixing bugs, and retesting would be considered as what type of waste? A. Waiting B. Over Production C. Defects D. Over Processing - ANSWER C. Defects Any effort spent on testing, bug fixes, and retesting would be considered as waste of type defects. If this was done right the first time, we would not have this waste. What is the need to plot data points on the least squares line if a probabilistic regression model exists? A. To visually present the relationship to others B. To check for fit; there may be a calculation error C. No rational reason for doing so D. To permit a projection outside of the test area - ANSWER B. To check for fit; there may be a calculation error The best answer is b. There may be a mathematical error. The second best answer is a. Answer option c is incorrect and option d is always risky. A team of Six Sigma has reached the control stage of DMAIC. The team has successfully reduced the defect of fabric critical stains from 73 to 1 per fabric roll. Now what type of control chart should the team recommend? A. A control chart based on the normal distribution such as the X-bar chart B. A control chart based on the Poisson distribution such as the u-chart C. A p-chart based on the binomial distribution D. An np chart based on the binomial distribution - ANSWER B. A control chart based on the Poisson distribution such as the u-chart All four answers refer to valid control charts, but only answer B recognizes the Poisson nature of the improvement achieved. Critical stains are defect counts which are descriptive of the Poisson distribution. All other chart options are improper applications. Option b is correct What would be considered the most important element in the deployment of Six Sigma? A. Training B. Organizational structure C. Management support D. Reward and recognition - ANSWER C. Management support All of the answer choices are key Six Sigma elements. However, the question states the "most important element." Management support is the most important element listed. What is the attempt to reduce the impact of human error in a process called? A. Poka-yoke B. Jidohka C. Kaizen D. Muda - ANSWER A. Poka-yoke What is the major weakness of the one-factor-at-a-time experimental strategy? A. It offers no ability to vary factors together. B. It fails to account for interactions between factors. C. It can be more costly to conduct. D. It is less efficient than designed experiments. - ANSWER B. It fails to account for interactions between factors. All the items present good arguments against the one-factor-at-a-time testing. However, the major disadvantage is the failure to account for interactions. So answer b is correct. Process capability (Cp) describes a process, often in a stable manufacturing environment, which leads to the production of a product that conforms to client and design specifications. What will be the Cp value of an ideal process? A. Greater than 1 (>1) B. Less than 1 (<1) C. Equal to 1 D. Within 1 standard deviation of mean - ANSWER A. Greater than 1 (>1) An ideal process will have a Cp value > 1 in a stable environment. Option a is the correct answer. What does OEE stands for? A. Overall Equipment Effectiveness B. Overall Estimation Effectiveness C. Overall Equipment Estimation D. Overall Effective Estimation - ANSWER A. Overall Equipment Effectiveness The determination of temporal variation in multi-vari charting means: A. Variation within piece B. Variation over time C. Variation piece-to-piece D. Variation within batch - ANSWER B. Variation over time Temporal variation means variation over time Which of the following pairs is the most useful in preparing control charts, when used together, for variables data? A. AQL, p-bar B. p, n C. X-bar and R D. R, sigma - ANSWER C. X-bar and R An X-bar and R chart are represented best by variables data. Options a and b list attribute data quantities. The two values in option d are measures of dispersion and are not used together in control charting. So option c is correct. Which of the following describes internal failure costs? A. The economic costs associated with a catastrophic failure of an internal subsystem B. The unavoidable quality system costs associated with the production of any product or service C. The opposite of external failure costs D. The costs resulting from a nonconformance detected before a product or service is provided - ANSWER D. The costs resulting from a nonconformance detected before a product or service is provided The nonconformance costs are related to processes that do not match the customer expectations and hence relate to internal failure costs. If an experiment has an alias, you could say that the two factor effects are: A. Confounded B. Blocked C. Misnamed D. Mixtures - ANSWER A. Confounded A design alias implies that the two factor effects are confused or confounded with each other. So option a is correct. Why would a Six Sigma practitioner use an EWMA chart? A. To identify special cause variation B. To identify common cause variation C. To identify small shifts in variation D. To take advantage of the fact that it's easier to use - ANSWER C. To identify small shifts in variation An Exponential Weighted Moving Average, or EWMA, chart is primarily used to indicate small shifts in process variation. What is the definition of Inventory type of waste? A. Storing parts at other location B. Any supply in excess to process requirements necessary to produce goods or services just-in-time C. Wrong parts in inventory D. Finding and removing defective inventory from the stock - ANSWER B. Any supply in excess to process requirements necessary to produce goods or services just-in-time Inventory type of waste refers to any supply in excess to process requirements necessary to produce goods or services just-in-time. So the correct answer is option b. Choose the control chart that is used to monitor discrete data in Lean Six Sigma Green Belt? A. p Chart B. I -MR Chart C. X Chart D. R Chart - ANSWER A. p Chart p Chart is the control chart that is used to monitor discrete data in Lean Six Sigma Green Belt. Which type of control chart is ideal for destructive testing? A. X bar chart B. p chart C. I chart D. u chart - ANSWER C. I chart The control chart that works best for destructive testing is an I chart since only one unit is required to plot results at a sing point in time. Which of the following is NOT a direct benefit of a Six Sigma project? A. Helps improve Cost of Quality B. Helps improve Customer Satisfaction C. Helps improve Supplier Quality D. Helps improve market share - ANSWER C. Helps improve Supplier Quality Six Sigma project helps in improving COQ, customer satisfaction, and also market share by increase in number of customers. Improving supplier quality is not a direct benefit of a Six Sigma project thus option c is the correct incorrect answer. When put together, what do Repetition and Replication help the Six Sigma team