IASSC Green Belt Study Guide Questions

IASSC Green Belt Study Guide Questions with 100% Correct Answers | Verified | Latest Update Question: 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? Correct Answer: (0.01)^5 Question: Who should complete the control phase after the successful completion and implementation of the first four phases of DMAIC? Correct Answer: The complete team is the most desirable option. Question: To increase the power of experiments, what is the best option in the hands of the Six Sigma team? Correct Answer: Increase sample size Question: Which of the techniques used in DOE helps you in eliminating errors due to nuisance factors? Correct Answer: Blocking Question: Hypothesis testing is usually done to: Correct Answer: Statistically validate if the sample mean belongs to the population. Statistically validate if means of two groups are the same or if they are significantly different. Statistically validate if variances of two groups are the same or if they are different. Question: What is the concept behind PDCA? Correct Answer: Continuous improvement Question: What are the experiments called while performing one experiment with five repetitions? Correct Answer: Replications Question: Which type of chart is used for small shifts in variation? Correct Answer: CUSUM Question: What are the distinct types of variation that are displayed in control charts? Correct Answer: Chance (common or random) and assignable (special). Question: Which of the following is an advantage of the production of a product in large lots? Correct Answer: Machine efficiencies Question: A sample is to a statistic as a population value is to a: Correct Answer: Parameter Question: 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? Correct Answer: A reproducibility of zero means there is no operator effect on this measurement. Question: 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? Correct Answer: 0.180 or 18% Question: Why are scatter diagrams useful in problem-solving? Correct Answer: They show relationships between variables. Question: The advantage of using the modern designed method of experimentation, rather than the classical OFAT, is that: Correct Answer: Fewer terms and measurements are needed for valid and useful information. Question: What does ANOVA stand for? Correct Answer: Analysis of variance Question: Which quality tool would not be expected to be used during the results confirmation stage of a problem solution? Correct Answer: Flow chart (Note: Use a process flow chart in the Define and Measure stage.) Question: 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? Correct Answer: Lot-to-lot variation Question: Which of the following inference tests does NOT require the knowledge of a test or population variance? Correct Answer: Chi-square test Question: Which of the following is the LEAST likely candidate to assist in the problem definition stage of Six Sigma? Correct Answer: Control charts (Note: Control charts are used in the Measure and Control phases.) Question: 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. Correct Answer: Collinearity Question: 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? Correct Answer: 0.25 (additive rule) Question: A process has a high variability and an off-centered mean. What is the first action the team needs to take? Correct Answer: Center the mean Question: What is the use of scatter diagrams? Correct Answer: Display correlation Question: 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? Correct Answer: 2.8 Question: In the IT sector, time and effort spent in testing the software, fixing bugs, and retesting would be considered as what type of waste? Correct Answer: Defects Question: What is the need to plot data points on the least squares line if a probabilistic regression model exists? Correct Answer: To check for fit; there may be a calculation error. (Note: 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.) Question: 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? Correct Answer: A control chart based on the Poisson distribution such as the u-chart. Control Chart Selection Guide Continuous Data: I-MR Chart: individual data points, destructive testing. Xbar and R Chart: subgroups (n is between 2 and 9). Xbar and s Chart: subgroups with SD (n >= 10). Discrete Data (constant or varying subgroup size): np Chart: Defectives, # of units rejected (constant subgroup size). p Chart: Defectives, % of units rejected (varying subgroup size). c Chart: Defects, # of defects (constant subgroup size). u Chart: Defects, average # of defects (varying subgroup size). Question: What would be considered the most important element in the deployment of Six Sigma? Correct Answer: Management support Question: What is the attempt to reduce the impact of human error in a process called? Correct Answer: Poka-yoke Question: What is the major weakness of the one-factor-at-a-time experiment strategy? Correct Answer: It fails to account for interactions between factors. Question: What would be the Cp value of an ideal process? Correct Answer: Greater than 1 (>1) Question: What does OEE stand for? Correct Answer: Overall Equipment Effectiveness Question: The determination of a temporal variation in multi-vary charting means: Correct Answer: Variation over time Question: Which of the following pairs is the most useful in preparing control charts, when used together, for variables data? Correct Answer: X-bar and R Question: Which of the following describes internal failure costs? Correct Answer: The costs resulting from a nonconformance detected before a product or service is provided. Question: Choose the control chart that is used to monitor discrete data in Six Sigma. Correct Answer: p Chart Question: If an experiment has an alias, you can say that the two factor effects are: Correct Answer: Confounded Question: Why would a Six Sigma practitioner use an Exponential Weighted Moving Average (EWMA) chart? Correct Answer: To identify small shifts in variation Question: What is the definition of inventory type waste? Correct Answer: Any supply in excess process requirements necessary to produce goods or services just-in-time. Question: Which type of control chart is ideal for destructive testing? Correct Answer: I chart (since only one unit is required to plot results at a single point in time). Question: Which is NOT a direct benefit of a Six Sigma project? Correct Answer: Helps improve Supplier Quality Question: When put together, what do Repetition and Replication help the Six Sigma team determine? Correct Answer: Short-term and long-term variability (Repetition = short-term; Replication = long-term). Question: What is NOT true in regard to regression analysis? Correct Answer: Least squares is required to determine the best fit straight line. (It is the most common procedure but other procedures are available). Question: 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? Correct Answer: Checklists and flow charts Question: Why are control chart subgroup sizes generally 3, 4, 5, or 6? Correct Answer: They are large enough so that averages of data will follow the normal distribution. Larger sizes permit an opportunity for process changes within the subgroup. They permit a separation of within-time from time-to-time variation. Question: What is the variance for a distribution of means with a sample size of 36 and a population standard deviation of 3? Correct Answer: 0.25 (Formula: standard deviation / square root of n, squared -> 3/sqrt(36) = 0.5; 0.5 squared = 0.25). Question: What is NOT an advantage of control charts? Correct Answer: They provide straightforward, easily interpreted information. Question: What is the most important benefit of implementing Lean? Correct Answer: Achieving continuous flow of product Question: Which tool should the team use to determine all the potential pitfalls and the actual defects that occur? Correct Answer: Process FMEA Question: What is the sampling error called when only 6% of customers return mailed surveys? Correct Answer: Non-response error Question: Which approach talks about equipment effectiveness? Correct Answer: TPM (Total Productive Maintenance) Question: Which Six Sigma role is most likely to define objectives for an improvement team? Correct Answer: Sponsor Question: What is accuracy? Correct Answer: Getting an unbiased true value (i.e., bias, linearity, and stability). FYI: Getting consistent results repeatedly = precision (i.e., repeatability and reproducibility). Question: What should the Six Sigma Green Belt do in terms of actions if Cp = 1.3 and Cpk = 0.8? Correct Answer: Center the mean (Cpk considers centering; if they aren't equal, the process is not centered). Question: Which of the following is used to test the equality of medians from two or more different populations? Correct Answer: Mood's Median Question: While plotting a multi-vary chart, what metric is used for the horizontal scale? Correct Answer: Time (Y-axis: continuous; X-axis: discrete, e.g., shift, employee). Question: What is the basic assumption of a null hypothesis? Correct Answer: That the variables are independent. Question: What does an F distribution closely resemble? Correct Answer: A chi-square distribution (since it is the ratio between two sample variances). Question: In hypothesis testing, if someone stated one minus the level of confidence, then which of the following statistics would be under consideration? Correct Answer: The alpha risk Question: Which best defines "Overproduction" type of waste? Correct Answer: Producing in excess over the need of a specified amount. Question: A "pull" production system is where you make as much product as you can regardless of whether the customer needs it or not. True or False? Correct Answer: False Question: What other characteristic will support a decision to use a fractional factorial instead of a full factorial? Correct Answer: The process is well known and only the main factors are of concern. Question: In the theory of control charts, the distribution of the number of defects per units that vary closely follows the: Correct Answer: Poisson distribution (as it is assumed for defects). Normal: variable data Chi-square: variance Binomial: defectives Question: What are the typical phases of the Six Sigma improvement methodology? Correct Answer: DMAIC (Define, Measure, Analyze, Improve, Control) Question: Which tool used in Six Sigma DMAIC implementation resembles the Process Decision Program Chart (PDPC)? Correct Answer: FMEA (Primary purpose of PDPC/FMEA is to limit risk and avoid failure). Question: Identify the post-improvement tool which would be most beneficial when generating fresh ideas after results have been disappointing. Correct Answer: A post-improvement brainstorming session Question: What type of waste is "Patient is ready to be seen but doctor is not available?" Correct Answer: Waiting Question: Identify the relationship between Waste and Defect. Correct Answer: Defect is a type of waste. Question: Which of the following terms is closely identified with the term "community"? Correct Answer: Society Question: A scoop samples 100/trial. What must be the average number of defects to be an 80% chance that more than one defect will be found in the sample? Correct Answer: 3 (Requires using the Poisson table in reverse). Question: What is the key benefit of multi-vary charting? Correct Answer: It assists in the breakdown of components of variation (positional, cyclical, and temporal) so that improvements can be made. Question: When a single gage is checked by comparing the results of different operators taken at different times, a reference is being made to: Correct Answer: Reproducibility Question: For 5 factors and 2 levels, the DOE setup has 16 runs. What type of experiment is being conducted? Correct Answer: Half-fractional factorial (Total runs = levels^factors; 2^5 = 32. 16 is half of 32). Question: Which control chart would best fit a process in which measurement data on a product is easily obtained? Correct Answer: X-bar and R charts Question: What is takt time? Correct Answer: Average customer demand for an article Question: Which is the one way to analyze variance by ranks? Correct Answer: Kruskal-Wallis (Mann Whitney U and Freidman test also analyze variance ranks). Question: What are the factors that impact the shape of the t distribution? Correct Answer: Sample size and degree of freedom Question: What part of 5S promotes all work stations for a particular job being identical? Correct Answer: Seiketsu (Standardize) Question: A process A, B, and C are working in series with yields as A=94%, B=98%, C=99%, then the total DPU is: Correct Answer: 9 per 100 (AxBxC = 91.19%. TDPU = -ln(RTY) = 0.09 = 9 per 100). Question: Which statistic can be used to determine the probability of variances occurring? Correct Answer: Chi-square statistic Question: What should practitioners be very sensitive to while plotting control charts? Correct Answer: 1) Type of charts selected, 2) Subgroup size chosen, 3) Interpretation of the charts. Question: To state that a model in an experiment is fixed indicates that: Correct Answer: The levels used for each factor are the only ones of interest. Question: In single-factor ANOVA, the assumption of homogeneity of variance applies to: Correct Answer: The variances within the treatment groups (natural variation within each treatment is the same). Question: Using which of the following tools can basic information about data, such as central location, width, spread, and shape be visualized? Correct Answer: Histograms Question: Who is NOT typically a relevant stakeholder in an important project? Correct Answer: Potential competitors Question: To determine the number of defective chips from each batch of inspected products, what type of chart should managers use? Correct Answer: P chart (used for discrete data; percentage of units rejected). Question: Which of the 5S techniques is the first step in 5S implementation? Correct Answer: Seiri (Sort) Question: The UCL and LCL on a traditional control chart are set how many standard deviations below and above the average? Correct Answer: 3 Question: Which of the following can a Six Sigma project reduce? Correct Answer: Total Failure Cost (internal and external) Question: For a full factorial experiment with 23 treatments and 1 replicate, how many runs can you expect? Correct Answer: 46 (23 + 23) Question: Which tool is specifically designed to identify risks of a potential solution? Correct Answer: FMEA Question: After a solution pilot is deployed, what type of hypothesis test should be used? Correct Answer: Paired t-test Question: A sample ______ is used to make inferences about the population ______. Correct Answer: Statistic; Parameter Question: Who will be the primary user of the control plan? Correct Answer: Process Owner Question: What is the appropriate mathematical model to describe the sampling distribution of the fraction defective in a sample from a controlled process in which p bar = 0.05? Correct Answer: The binomial distribution in which p bar = 0.05. Question: For a process working at 3 Sigma level, how many opportunities out of one million are considered to lie outside of the specification limits? Correct Answer: 66,807 Sigma Level Table (DPMO / Accuracy) 6 Sigma: 3.4 DPMO / 99.99966% 5 Sigma: 230 DPMO / 99.9% 4 Sigma: 6,210 DPMO / 99.4% 3 Sigma: 66,800 DPMO / 93.3% 2 Sigma: 308,000 DPMO / 69.2% 1 Sigma: 690,000 DPMO / 30.1% Question: In which stage of a DMAIC approach should the Six Sigma team decide on making a flowchart or value stream map? Correct Answer: Analyze Question: In terms of ease of understanding and implementation, which tool is considered best to inform employees of their work roles? Correct Answer: Written instructions Question: Which of these are categorized under Precision in a Gage R&R study? Correct Answer: Repeatability and Reproducibility Definitions: Reproducibility: Variation in measurements obtained with one instrument used several times by different operators. Repeatability: Variation in measurements obtained with one instrument used several times by one operator. Question: 1-sample Sign test / 1-sample Wilcoxon: Correct Answer: median (Dependent sample t or Z test) Question: Mann Whitney U: Correct Answer: ranks (Independent samples t or Z test) Question: Kruskal-Wallis: Correct Answer: ranks based on chi-square (One-Way ANOVA alternative) Question: Mood's Median: Correct Answer: median based on chi-square (One-Way ANOVA alternative) Question: Freidman test: Correct Answer: ranks based on chi-square (Repeated measures ANOVA alternative) Question: Bias / Linearity / Stability: Correct Answer: Measures of accuracy (Bias = distance from true value; Linearity = consistency over range; Stability = consistency over time). DMAIC Phases Define: Define the problem, project goals, and customer deliverables. Measure: Measure the process to determine current performance; quantify the problem. Analyze: Analyze and determine the root cause(s) for variation and defects. Improve: Develop, test, and implement solutions to improve the process. Control: Control future process performance by monitoring key factors. Tools by Phase Define Tools: Project charter, Process flowchart, SIPOC Diagram, Stakeholder Analysis, Voice of the Customer, Affinity Diagram, CTQ Definitions, QFD, FMEA. Measure Tools: Process flowchart, Data Collection Plan, Benchmarking, MSA/Gage R&R, Control charts, Process capability, Process Sigma Calculation. Analyze Tools: Histogram, Pareto chart, Run chart, Scatter plot, Regression Analysis, Cause and Effect Matrix/Fishbone, 5 Whys, FMEA, Multi-vari charts, Hypothesis testing. Improve Tools: Brainstorming, Piloting, Mistake Proofing, DOE, Pugh Matrix, QFD, FMEA. Control Tools: Process Sigma Calculation, Control charts, Cost/Benefit Analysis, Control plan, MSA. Question: Who would be the focused audience for a project aimed at training people, job instructions, and employee surveys? Correct Answer: Internal customers Question: The Cause and Effect Diagram with the 5 Whys helps the team know what? Correct Answer: The assignable root causes Question: In embracing Six Sigma, what has been the principle motivating factor from the point of view of upper management? Correct Answer: Bottom line results Question: What is the purpose of Rolled Throughput Yield (RTY)? Correct Answer: 1) Analyze a process flow for improvement ideas, 2) spot significant differences in yield, and 3) provide a baseline metric. Question: A company making rubber tires is evaluated on 5 opportunities per product; in 1000 products manufactured, if 100 defects are observed, the RTY is: Correct Answer: 98% (DPU = 100/5000 = 0.02; Y = e^-0.02 = 0.98). Question: When samples are drawn out of a population randomly, what is said to be true? Correct Answer: The sampling distribution approaches normality with increases in sample size. Question: Which of the following cannot be considered as an acceptable reason for deploying a Six Sigma DMAIC project? Correct Answer: Improve the design Question: Sum Square of Error is equal to: Correct Answer: Sum Squares due to Pure Error + Sum Squares due to Lack of Fit Question: The p value for Mood's Median test is .02 and the level of significance is .05, what decision is made? Correct Answer: Reject null hypothesis Question: Which of the following tools helps in visualizing series of causes to an effect? Correct Answer: Ishikawa Diagram Question: Which of the following statistical tests should be used by the Green Belt for testing the means between two inter-related groups? Correct Answer: Paired t-test Question: Standard deviation in Six Sigma applications is referred to as difference from the: Correct Answer: Mean Question: In a typical DFSS approach, which these stage figures in most DFSS approaches? Correct Answer: Identify (Steps: Identify, Design, Optimize, Verify). Question: Which activities is NOT non-value added? Correct Answer: Process (Non-value added examples: setup, rework, inspection). Question: Identify the most accurate method for qualifying gage repeatability and reproducibility. Correct Answer: The ANOVA method Question: Why would Six Sigma activities prompt a re-analysis of measuring systems? Correct Answer: Variability may be reduced, requiring more precise measurements. Question: The linking or prioritization of customer wants into engineered values occurs in which element of the House of Quality? Correct Answer: Relationship matrix Question: What type of variation does a process have if it is "in control"? Correct Answer: Process has random causes only Question: Which of the following techniques used in DOE helps you in identifying pure error? Correct Answer: Replication Question: What can be stated about a combined R&R ratio of 7.42% of process tolerance? Correct Answer: The measurement system is acceptable. (<10% acceptable; 10-30% marginal; >30% not acceptable). Question: A perfect regression model with all points fitting the regression line has Sum of Square Errors ______. Correct Answer: Equal to 0 Question: Randomization - Correct Answer: Correct Answer: Frees an experiment from the environment and other biases by running the trial without any order. Question: If men having high blood sugar problems are diagnosed with diabetes with a mean level of 120 and SD of 9, and any individual over 100 can be diagnosed, what is the probability of a Type II error? Correct Answer: 0.0139 (Z = (100-120)/9 = -2.2. Area under Z table is 0.0139). Question: To optimize the response of a process, ideally what sequence of experimentation should one use? Correct Answer: Use screening first and then response surface techniques. Question: What is the process capability for attribute data? Correct Answer: The average proportion of nonconforming product. Question: Hypothesis tests on enumerative statistics (counted data) would NOT involve which distribution? Correct Answer: Student's t Question: Which distribution is the term "degrees of freedom" inapplicable? Correct Answer: Poisson Question: Which of the following is an example of a primary metric for Six Sigma projects? Correct Answer: Quality (Secondary: morale, turnover, customer satisfaction). Question: Which of the following errors is typically associated with the notion, "False negative"? Correct Answer: Type II error Question: The best metric for measuring defectives is: Correct Answer: Parts Per Million (PPM). Formula: (total # defectives / sample size) x 1,000,000. Definitions: DPU (Defects Per Unit): total # defects / sample size. DPMO (Defects Per Million Opportunities): (total # defects / total # defect opportunities) x 1,000,000. Question: In a typical MSA Gage R&R study, what should the team determine first? Correct Answer: Resolution (or Discrimination) Question: The differences between actual response data and the model data are termed as: Correct Answer: Residuals Question: Which of the following is NOT necessary for the Six Sigma team to update in the project charter in the Define Phase? Correct Answer: Constraints Question: Which of the following distributions describes the ratio of two variances drawn from the same normal population? Correct Answer: F statistic Question: Least squares method - Correct Answer: Correct Answer: A method to create the best-possible approximation of a line given the data set. Question: Six Sigma - Correct Answer: Correct Answer: Quality and Effectiveness: Breakthrough processes, identifying root cause, and variation reduction. Question: Sum of Squares - Correct Answer: Correct Answer: A statistical method to know the data dispersion and determine mathematically the best fit model in regression analysis. Large values indicate large variance.