Six Sigma Green Belt, The Analyze Phase / The Improve Phase practice test with complete verified solutions 2024 latest update

What is the key difference between prevention and mitigation? Prevention includes activities such as error proofing or taking in account the process capabilities and performance of a current process to understand characteristics while mitigation reduces the seriousness of an issue from arising but will not eliminate it altogether What tool would you use to determine whether the source of variation is due to within-piece, piece-to-piece, or time-to-time? Multi-vari chart Explanation: B is true because the multi-vari tool shows you the enemy, and the enemy is variation. This tool separates variation into three possible sources - within-piece, piece-to-piece, and time-to-time. Choices A, C, and D are not true because these tools are snapshots of process variation. They tell you nothing about the source of variation. Brainpower Read More How is waste defined in terms of the Lean approach? Any activity that consumes resources but creates no value for the customer Explanation: Waste is any activity that consumes resources, but creates no value for the customer. Required waste is non-value added but necessary for the current process while pure waste adds nothing to the process. How can the Pareto diagram help you narrow the list of potential root causes? It tells you which things occur most frequently Explanation: The Pareto diagram is a great option to rank the issues. It will tell you which things occur the most often. What varies more; averages or individuals? Individuals vary more than averages The null hypothesis is What we expect to happen due to chance alone Explanation: The null hypothesis is what we would expect due to chance alone - and is assumed to be true (so it cannot ever be proven true). Why is the improve phase so important to the process? It forces you to choose the best solution Explanation: The improve phase is critical because it forces you to choose from options and select the best solution. What does 5S stand for? Sort, set in order, shine, standardize, sustain Which of the following is a reason to conduct your trials randomly? Minimizes confounding of variables with noise Explanation: Randomization means noise factors are equally as likely to be present in all trials. Why must you take a structured approach to root cause analysis? To find the true cause of the problem and implement a permanent fix Explanation: Root cause analysis includes a very structured approach to investigating issues for a permanent fix of the problem. What is sought after is the true cause of the problem, which most people mistake with short-term fixes. What is a Risk Priority Number? Severity, occurrence, and detection together If you perform a chi-square test on data collected on religion and median income of residents in a certain county, and you calculate a test statistic of 6.74, and look up a critical value of 5.99 in the chi-square table, what would your hypothesis conclusion be? Religion and median income are dependent Explanation: A chi-square tests the null hypothesis that two factors are independent (what we would expect due to chance alone). That the two factors are dependent is the alternative hypothesis. When using a control chart, one should gather data In the order of production Explanation: In the order of production. The ease of data collection is not a major consideration. It is more important to collect data that relates to a critical product or process parameter. What should you have accomplished by the end of the analyze phase? Identified the critical root causes to improve; Used graphical tools to narrow the list of possible root causes; Generated a large list of possible root causes; Explanation: At the end of the analyze phase, you should have identified the possible causes, narrowed the list, and identified the ones you plan to pursue. During the critical root causes tollgate, what do you need to prove to the sponsor? That eliminating the critical root causes will close gaps in performance Explanation: The bottom line is that you need to demonstrate to the sponsor that eliminating these critical few will improve our effectiveness and efficiency to the levels we and our customers want. What is a type I error? When we reject the null, when it fact the null was true Explanation: A type I error, also known as an Alpha error, occurs when the test stat falls in the critical/rejection region - even though the null was true. When should you pilot your solutions? When costs of failure is high; When reversal is difficult; They may be unintended consequences Explanation: It is better to test a solution on a smaller scale to minimize the risk of a full-scale implementation that could be costly or result in severe consequences. Which of the following are good uses of the F-test for hypothesis testing? To test the null hypothesis that two normal populations have the same variance;To test the null hypothesis that two normal populations with the same standard deviation have the same mean;A one-way ANOVA Explanation: All three examples are cases where the F-test would be used. When using a one-tailed test and a sample size of 24, what is the probability of a value being to the left of a number that has a student-t statistic of -2.50? 1% Explanation: The t-distribution is symmetric, so looking up something for the probability of a value being to the left of - is the same as looking up the probability of a value being to the right of . Since the sample size is 24, the df are 23. Reading across the row for df 23 we see that 2.500 is in the column for alpha = 0.01. Since this is a one-tailed test all of alpha is in the one tail, and that makes the probability 1%. What is NOT a benefit of a value stream map? Details specific steps and decision points Explanation: Value stream maps show a view of the process from the perspective of the customer, allow everyone to see the waste in the process, and show both the flow of material and the flow of information. Decision points are diamonds on flowcharts, and do not appear in a Value Stream Map. The F-statistic is a ratio of what? Variances Explanation: The F-statistic is a ratio of variances. In a one-way ANOVA, how do we calculate the df error value? df total - df factor Explanation: The df error is the difference between the df total and the df factor. The df total is found by taking the sum total of all sample sizes and subtracting 1. Answer A is incorrect because we do not know the number of unknown sources of variation (they are unknown, by definition). Which of the following is a good situation to use the student-t distribution? When trying to validate a claim about a population mean given a sample set of 20 pieces of data Explanation: The student-t distribution is used to compare the sample mean from a data set of less than 30 to the known (or claimed) population mean. A is incorrect because we would use the standard normal distribution for a sample size of greater than 30. C is the F-distribution, and D is the chi-square distribution. What is the purpose of Lean? Understanding and eliminating waste in a process Explanation: Lean is about creating value for the customer and utilizing fewer resources. When investigating potential root causes, what might be useful if the list becomes overwhelming? Group them into meaningful categories but keep the full list Explanation: If the list of potential root causes is overwhelming, you might want to group them into meaningful categories. But you should have a full list and keep them in a real document. What are the elements of a good implementation plan? People, budget, change management, time line, and measures for success What do you need to calculate Z-scores? The mean of the sample You are trying to determine if the average call length at a call center has decreased since you have introduced process improvements. You will use hypothesis testing to do this. What is the alternative hypothesis? The average call time after the changes is less than the average call time before the changes Suppose the top 15 percent of producers get bonuses and the average production rate is 200 units with a standard deviation of 20. What would be the Z-score of someone who produces 240 units? 2 This method of designed experiment allows for the study of ALL main effects and interactions Full factorial