FINAL 2 Flashcards
_____is a convenient way of visually displaying the data distribution through their quartiles to compare distributions and variations.
a.
SIPOC
b.
A box plot
c.
A Pareto chart
d.
An X-Y diagram
A box plot is a simple way of representing statistical data on a plot in which a rectangle is drawn to represent the first (lower) and third (upper) quartile values, usually with a vertical line inside to indicate the median (second quartile) value.
A Belt has conducted a gage R&R study to evaluate the measurement system. As a result, she got 33% R&R tolerance and 2 as the NDC value in the output. As per AIAG guidelines, what should she decide about the measurement system?
a.
Accept the MSA, as the percent tolerance is large.
b.
Do not accept the MSA.
c.
Marginally accept the MSA, as the NDC value is 2.
d.
Decide based on the business process being monitored.
As per AIAG guidelines, in a gage R&R study for variable data, the measurement system is acceptable if percent tolerance is less than 10% and the NDC is more than 4. It can be marginally acceptable for a percent tolerance value in the range of 10%–0%. However, for a percent tolerance more than 30%, the measurement system is not acceptable.
GAGE R&R 10%-30%= ACCEPTABLE
GAGE R&R OVER 30%= UNACCEPTABLE
NDC LESS THAN 5=ISNT ENOUGH PART VARIATIONS
ANOVA CHART
A Belt has conducted a regression analysis and may find the fact that:
a.
r-square value is smaller than the absolute value of r.
b.
Correlation coefficient equals r-square.
c.
Coefficient of determination is less than r-square.
d.
Correlation coefficient equals r divided by sqrt 2.
alues of correlation coefficient r: -1 ≤ r ≤ +1, but r² < |r|, for any value of r just less than +1 or just greater than -1.
A Belt is creating a macro process map in order to describe a complex process. She is interested in including activities across different departments. What should the Belt use to capture the process steps along with their responsible departments?
a.
SIPOC
b.
Organization chart
c.
Swim lane
d.
Project charter
A swim lane is a visual representation used in process flowcharts or process mapping that visually displays individual responsibilities or assignments for subprocesses of a business process.
A Belt is evaluating the impact of solutions and proposed improvements for the ongoing Six Sigma project. Which key elements should he take into account?
a.
Management views
b.
Implementation time, cost, and solution effectiveness
c.
Project champion’s and team’s preferences
d.
Cost and resources
The solution implementation time frame, cost, and improvement effectiveness are important to consider while evaluating the impact of solutions in a Six Sigma project. All other options are either secondary or do not need to be considered.
A characteristic was inspected in a sample of 1,000 orders, of which 25 orders were found to be incorrect, but 20 of these orders were reprocessed to correct them. What is the throughput yield (TPY) of this process?
a.
0.9
b.
0.95
c.
0.99
d.
0.975
TPY = 1 − (rework + reject)/input. TPY = 1 − 25/1000 = 1 − 0.025 = 0.975.
A linear regression model shows an R-squared (adjusted) of 0.90 and a p-value of 0.002. What can you conclude?
.
a. Variability is well explained by the regression model.
b.
Only 10% of the variability is explained by the model.
c.
There is a significant impact of the independent variables on the dependent variable.
d.
There is a significant impact of the independent variables on the dependent variable, and variability is well explained by the regression model.
e.
Only 10% of the variability is explained by the model; however, there is a significant impact of the independent variables on the dependent variable.
D. R-squared is a statistical measure of the proportion or percentage of variation in the dependent variable that can be predicted from the set of independent variables in a regression model. It is also known as the coefficient of determination, or the coefficient of multiple determination for multiple regression. A figure of 100% indicates that the model explains all the variability of the response data around its mean.
A plastic box manufacturer is producing four types of boxes. A quality engineer is working on reducing the variances of the storage capacity of boxes. To explain the variation of storage capacity across all types of boxes, which sampling method should he use?
C. In random sampling, each member of the subset carries an equal opportunity of being chosen as a part of the sampling process.
A production manager wants to evaluate the measurement system for one of the key processes. The true value of pitch of the screw is 10 mm. She measures the same fastener six times and the measured data for the pitch (mm) is as follows: 12, 11.5, 12, 12, 11.5, 12 What should she infer about the measurement system?
a.
Accurate, but not precise
b.
Precise, but not accurate
c.
Both accurate and precise
d.
Neither precise nor accurate
B. Since all the readings are very close, the measurement system is precise in producing consistent results for repeated measurements. However, these measured values are very different from the actual value of 10 mm, so the system is not accurate.
A time series plot with statistical boundaries is called a:
a.
Run chart.
b.
Probability plot.
c.
Control chart.
d.
Box plot.
e.
Scatter plot.
C. Control charts and run charts are time series plots. In a control chart, statistical process control limits are drawn as upper and lower boundaries. Unlike a control chart, a run chart does not have any statistical control limits and is often used to study the stability of the process data. Probability plots and box plots help understand data distribution, while a scatter plot is used to graphically represent relations between two variables at a time.
A(n) ________ is used to determine whether the averages of normally distributed population samples differ from each other with statistical confidence.
a.
t-test
b.
chi-square test
c.
F-test
d.
DOE
A 2-sample t-test is used to compare the means of two independent samples that are normally distributed. A chi-square test is used for one normally distributed sample variance against the target. An F-test is used to compare variances of two normally distributed samples.
According to the central limit theorem, the sampling means distribution for a non-normal population converges to normal for a larger sample size.
a.
True
b.
False
true
An airline wants to improve the satisfaction level of its customers. The improvement project team collected the sample customer feedback data on flight service for a period of 2 months, and the results are shown in the figure below. They want to establish the baseline using the Z-score. What should they do before the Z-score calculation?
RATINGS COUNTS PROPORTION % AWESOME 30 21% VERY GOOD 67 48% GOOD 26 19% AVERAGE 12 9% BAD 5 4%
a.
Wait for more data.
b.
Consider average and bad ratings as defective and calculate Z for 12% proportion as defectives.
c.
Check the reliability of the bad ratings.
d.
The Z-score cannot be calculated using the given feedback data.
B. Average and bad rating data combined contribute to about 8.5% + 3.5% = 12% proportion. These ratings are below the satisfaction level of customers and should be treated as defectives. Therefore, we have 12% proportion defectives in the collected data, which should be used in the Z-score computation.
An EWMA chart with λ = 1 approximates to a(n):
a.
CUSUM chart.
b.
X-bar chart.
c.
C chart.
d.
MR chart.
B. When λ = 1 in an EWMA chart, the weightage is given to historical data; (1 − λ) in EWMA becomes zero. Therefore, we consider only current data in a control chart with λ = 1, which is the same as an X-bar control chart.
Appraisal cost and prevention cost are not examples of cost of poor quality, or COPQ.
a.
True
b.
False
A. Prevention and appraisal costs are required for Quality assurance. Both are considered the components of COPQ. These are costs for detection and prevention of product failures.
Box-Cox transformation can be used to:
a.
Convert the data from non-normal to normal.
b.
Convert the data from unstable to stable.
c.
Create the box plot.
d.
All of the above
A. A Box-Cox transformation is a way to transform non-normal data into a normal shape; however, normal conversion is not always guaranteed
Confidence interval is narrower than prediction interval in inferential statistics.
a.
True
b.
False
A. Confidence interval is the interval estimate around the sample statistic at a given confidence level, which represents the variability to contain population parameters, if many samples are drawn from that population repeatedly. Prediction interval, on the other hand, is the interval estimate around the sample statistics to predict an individual future observation instead of population parameters, such as mean. That’s why its range is wider than the confidence interval.
Contingency tables are used to compare more than two sample proportions with each other.
a.
True
b.
False
A. Contingency tables are used to simultaneously compare more than two sample proportions with each other. There are two separate tests for one sample proportion and two sample proportions.
During a Six Sigma project, a Belt has established a linear regression line with an equation of the form Y = 3.41 + 6.28X, where X is the independent variable and Y is the dependent variable. The value of 3.41 in the above equation is called the _____ and the value 6.28 in the given equation is the ______.
a.
intercept; slope
b.
slope; intercept
c.
x-intercept; slope coefficient
d.
slope; slope coefficient
A. In a simple linear regression model, we get output as an equation of a line with the slope and the Y-intercept of the line. In the equation Y = a + bX, b is the slope and a is they-intercept.
During new product development, Wilson wants to focus on the product reliability maximization using FMEA. Which stage of the development project is crucial to meet the objective?
a.
Testing
b.
Design
c.
Pre-launch
d.
Prototype
e.
Concept
B. The major influence of FMEA on the reliability maximization during product development happens in the design stage of the cycle. Typically, new product development starts with ideation, or the concept stage, followed by design, prototype, testing, and pre-launch. Reliability in the product is incorporated during design by analyzing potential design failures and addressing them.
Factory xyz is operating in two shifts. Quality supervisors of the first and second shifts are both claiming to have the highest quality shift. Yesterday, the second shift observed 3 defects out of 450 units produced, and the first shift found 5 defects out of 450 units. With this data, the management got the following output to draw the conclusion. Should management reward the second shift for the highest quality shift?
a.
Yes
b.
No
B. Since the p-value of the 2-proportion test here is 0.478, which is more than 0.05, we cannot reject the null hypothesis. Also, 95% CI contains zero within the interval boundaries -0.0078 and 0.0167, so, again, we cannot reject the null hypothesis.
Failing to reject a false null hypothesis is called a consumer’s error.
a.
True
b.
False
A. A type of error that can be made in significance testing is failing to reject a false null hypothesis. This kind of error is called a type 2 error or consumer’s error, and the probability of the error is known as the β (beta) risk.
Generally, a fishbone diagram is used in tandem with which of the following tool(s) and/or technique(s)?
a.
Brainstorming
b.
5 Whys
c.
FMEA
d.
Brainstorming and 5 Whys
e.
Brainstorming and FMEA
D. Its a common practice to use a cause and effect, or fishbone, diagram in conjunction with the 5 Whys and brainstorming. Brainstorming is useful to identify all probable causes leading to the given effect, and the 5 Whys help to eventually reach the root cause.
Hypothesis testing is about drawing conclusions for a population parameter or distribution.
a.
True
b.
False
A. Hypothesis testing is a form of statistical inference that uses data from a sample to draw conclusions about a population parameter or a population probability distribution.
If Y (dependent variable) is continuous and X (independent variable) is discrete, you can perform any of the following except:
a.
A t-test.
b.
A proportion test.
c.
A nonparametric test.
d.
An ANOVA test.
B. If the Y variable is continuous and the X variable is discrete, for normal data, a t-test, ANOVA test, F-test, and chi-square test can be done; for non-normal data, a nonparametric test and Levene’s test can be done. A proportion test is done when the Y variable is discrete and the X variable is also discrete.
In FMEA, RPN value is calculated for each potential failure mode. Which elements does this RPN calculation consist of?
a.
Structure, opportunity, and detection
b.
Failure, probability, and impact
c.
Severity, occurrence, and detection
d.
Failure, effect, and cause
C. In FMEA (failure mode and effects analysis), for each failure mode, severity, occurrence, and detection ratings are determined and RPN (risk priority number) is calculated. RPN is the product of these three ratings.
n order to standardize the calculation of financial savings of a project so that such project benefits can be compared, the financial savings are typically calculated over what period of time?
a.
24 months
b.
36 months
c.
The remainder of the calendar year
d.
12 months
D. The financial savings are typically calculated on an annual basis (12 months).
In the case of a ______ test, we will first have to decide whether we want to compare for an upper tail test or a lower tail test.
a.
one-tail
b.
two-tail
c.
regression
d.
chi-square
A. In the case of a one-tail test, we will first have to decide whether we want to compare for an upper tail test or a lower tail test. For example, in a 2-sample t-test, the upper tail test will check if the mean of sample 1 is significantly higher than that of sample 2. If the sample has a lower value, the null hypothesis will be selected. The exact opposite of this is the lower tail test, in which the null hypothesis will be rejected only if the mean of sample 1 is markedly lower than that of sample 2.
Kaikaku projects are intended to create incremental process improvements.
a.
True
b.
False
B. Kaikaku focuses the process improvement through radical changes. So a kaikaku is a breakthrough success that is the first focus of Six Sigma projects. Incremental improvement is an approach to process improvement in which the focus is on efforts toward incremental solutions that slowly but surely move the business toward success. Incremental improvement are similar to daily kaizen and kaizen events.
Lean originated from:
a.
GE.
b.
Ford.
c.
Toyota.
d.
Motorola.
C. TPS is the production system developed by the Toyota Motor Corporation to provide the best quality, lowest cost, and shortest lead time through the elimination of waste. It is known as “Lean.”
Lean removes waste from the process, while Six Sigma reduces variation in the process.
a.
True
b.
False
A. Lean removes many forms of waste so that Six Sigma can focus on reducing variability in the process.
Long-term data represent all the variations that one can expect within the subject process.
a.
True
b.
False
A. Long-term data contain both common and special causes of variation and are more representative of process performance over a period of time. Long-term data are thus helpful in the study of process stability.
