Module 1 - Quality Management

If the chance that any of five telephone lines is busy at any instant is 0.01, then what is the probability that all the lines are busy? - answer-(0.01)^5 Who should complete the control phase after the successful completion and implementation of the first four phases of DMAIC? - answer-The complete team is the most desirable option. To increase the power of experiments, what is the best option in the hands of the Six Sigma team? - answer-Increase sample size Which of the techniques used in DOE helps you in eliminating errors due to nuisance factors? - answer-Blocking Hypothesis testing is usually done to: - answer-1) Statistically validate if the sample mean belongs to the population, 2) statistically validate if means of two groups are the same or if they are significantly different, and 3) statistically validate if variances of two groups are the same or if they are different. What is the concept behind PDCA? - answer-Continuous improvement What are the experiments called while performing one experiment with five repetitions? - answer-Replications Which type of chart is used for small shifts in variation? - answer-CUSUM What are the distinct types of variation that are displayed in control charts? - answer-Chance (common or random) and assignable (special) Which of the following is an advantage of the production of a product in large lots? - answer-Machine efficiencies A sample is to a statistic as a population value is to a: - answer-Parameter 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? - answer-A reproducibility of zero means there is no operator effect on this measurement. The average number of major storms in a city is 2 per year. What is the probability that exactly 3 storms will hit next year? - answer-0.180 or 18% Why are scatter diagrams useful in problem-solving? - answer-They show relationships between variables. The advantage of using the modern designed method of experimentation, rather than the classical OFAT, is that: - answer-Fewer terms and measurements are needed for valid and useful information. What does ANOVA stand for? - answer-Analysis of variance Which quality tool would not be expected to be used during the results confirmation stage of a problem solution? - answer-Flow chart Use a process flow chart in the Define and Measure stage. 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? - answer-Lot-to-lot variation Which of the following inference tests does NOT require the knowledge of a test or population variance? - answer-Chi-square test Which of the following is the LEAST likely candidate to assist in the problem definition stage of Six Sigma? - answer-Control charts Control charts are used in the Measure and Control phases. Remember: The process must first be brought into statistical control by detecting and acting upon special causes of variation. Then its performance is predictable, and its capability to meet customer expectations can be assessed (Cp and Cpk), which is done in the Measure phase. What is the name of the condition if you are running a 7x4 fractional experiment, and 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. - answer-Collinearity 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? - answer-0.25 (additive rule) A process has a high variability and an off-centered mean. What is the first action the team needs to take? - answer-Center the mean What is the use of scatter diagrams? - answer-Display correlation 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 population mean? - answer-2.8 In the IT sector, time and effort spent in testing the software, fixing bugs, and retesting would be considered as what type of waste? - answer-Defects What is the need to plot data points on the least squares line if a probabilistic regression model exists? - answer-To check for fit; there may be a calculation error. The line fitted to the paired data points must be such that the sum of the squares of the vertical distances from the points to the line is as small as possible. 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? - answer-A control chart based on the Poisson distribution such as the u-chart. Continuous data: I-MR Chart (individual data points, destructive testing) Xbar and R Chart (subgroups) Xbar and s Chart (subgroups with SD) Discrete data (constant or varying subgroup size): np Chart (Defectives, # of units rejected) p Chart (Defectives, % of units rejected) c Chart (Defects, # of defects) u Chart (Defects, average # of defects) What would be considered the most important element in the deployment of Six Sigma? - answer-Management support What is the attempt to reduce the impact of human error in a process called? - answer-Poka-yoke What is the major weakness of the one-factor-at-a-time experiment strategy? - answer-It fails to account for interactions between factors. 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 would be the Cp value of an ideal process? - answer-Greater than 1 (1) What does OEE stand for? - answer-Overall Equipment Effectiveness The determination of a temporal variation in multi-vary charting means: - answer-Variation over time Which of the following pairs is the most useful in preparing control charts, when used together, for variables data? - answer-X-bar and R Which of the following describes internal failure costs? - answer-The costs resulting from a nonconformance detected before a product or service is provided. Choose the control chart that is used to monitor discrete data in Six Sigma. - answer-p Chart If an experiment has an alias, you can say that the two factor effects are: - answer-Confounded Why would a Six Sigma practitioner use an Exponential Weighted Moving Average (EWMA) chart? - answer-To identify small shifts in variation What is the definition of inventory type waste? - answer-Any supply in excess process requirements necessary to produce goods or services just-in-time Which type of control chart is ideal for destructive testing? (Destructive testing = a form of MSA where the part being measured is destroyed or altered, creating an issue in reproducibility.) - answer-I chart (since only one unit is required to plot results at a single point in time) Which is NOT a direct benefit of a Six Sigma project? - answer-Helps improve Supplier Quality When put together, what do Repetition and Replication help the Six Sigma team determine? - answer-Short-term and long-term variability What is NOT true in regard to regression analysis? - answer-Least squares is required to determine the best fit straight line. (It is the most common procedure but other procedures are available). What set of basic quality tools would be the most applicable for a work team to use when there is desire to follow procedures and work instructions more closely? - answer-Checklists and flow charts Why are control chart subgroup sizes generally 3, 4, 5, or 6? - answer-1) They are large enough so that averages of data will follow the normal distribution, 2) larger sizes permit an opportunity for process changes within the subgroup, and 3) they permit a separation of within time from time-to-time variation. What is the variance for a distribution of means with a sample size of 36 and a population standard deviation of 3? - answer-0.25 formula: standard deviation/square root of n, squared 3/sqrt(36) = 0.05 squared = 0.25 What is NOT an advantage of control charts? - answer-They provide straightforward, easily interpreted information. What is the most important benefit of implementing Lean? - answer-Achieving continuous flow of product