Question 1
What is the variance of a population?
A) It is the difference in creating process maps.
B) It is equal to the sum of the squared deviations from the mean, divided by the population
size.
C) It is equal to the standard deviation.
D) It is the sum of the mean, median, and mode.
ANSWER
B
The variance, σ^2, of a population is equal to the sum of the squared deviations from the
mean, divided by the population size. For a sample, the variance is equal to the sum of the
squared deviations from the mean, divided by the sample size − 1.
Question 2
T/F We should not try to interpret the X-bar chart if the R chart shows an out-of-control
condition.
ANSWER
True
We should first investigate the range chart if the control chart meets any out-of-control
conditions. The range chart represents within process variance over time. It is important
to fix the within variation before we interpret the X-bar chart.
1
,Question 3
In a hypothesis test for means, a sample size of 20 has produced a mean of 9.5 mm with a
standard deviation of 0.5 mm. The customer specification for the part is 10 mm. At 5%
significance level, what should the customer do?
A) State that the population mean is greater than 10 mm.
B) Change their specification to 9.5 mm.
C) Accept the lot.
D) Reject the lot.
ANSWER
D
t-value = (9.5 − 10)/(0.5 /sq. rt (20)) = -4.472 t-critical = t(0.025, 19) = - 2.093 (from t-table)
t-value = -4.472 < t-critical = -2.093. Reject the null hypothesis, meaning the lot mean is
not the same as the target or customer specification. The customer should reject the lot.
Question 4
Lean originated from:
GE.
Ford.
Toyota.
Motorola.
ANSWER
Toyota
2
,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."
Question 5
What is the minimum number of sample items required to carry out a meaningful Attribute
Agreement Analysis?
10
30
50
15
ANSWER
50
It is recommended to have at least 50 sample items in Attribute Agreement Analysis to
establish appropriate results.
Question 6
We use Cook's distance statistics to identify unusual data points or observations that
A) have multicollinearity.
B) deviate from the normality conditions.
C) influence the regression fit significantly.
D) Are equally spaced from the center.
3
, ANSWER
C
Cook's distance statistics is a measure of the distance between the fitted values calculated
with and without the ith observation. It is used to identify the unusual observations that
may have influence on the regression model.
Question 7
What is the advantage of using EWMA or CUSUM charts over conventional control charts?
Able to detect large process shifts
Easier in calculation
Very accurate
Able to detect small process shifts
ANSWER
Able to detect small process shifts
EWMA and CUSUM charts are able to detect any small shift (< 1.5 times sigma) in a
process, which is not possible with a conventional Shewhart control chart.
Question 8
T/F Mixed distributions form if data come from several sources that are expected to be the
same yet are not.
ANSWER
True
4
What is the variance of a population?
A) It is the difference in creating process maps.
B) It is equal to the sum of the squared deviations from the mean, divided by the population
size.
C) It is equal to the standard deviation.
D) It is the sum of the mean, median, and mode.
ANSWER
B
The variance, σ^2, of a population is equal to the sum of the squared deviations from the
mean, divided by the population size. For a sample, the variance is equal to the sum of the
squared deviations from the mean, divided by the sample size − 1.
Question 2
T/F We should not try to interpret the X-bar chart if the R chart shows an out-of-control
condition.
ANSWER
True
We should first investigate the range chart if the control chart meets any out-of-control
conditions. The range chart represents within process variance over time. It is important
to fix the within variation before we interpret the X-bar chart.
1
,Question 3
In a hypothesis test for means, a sample size of 20 has produced a mean of 9.5 mm with a
standard deviation of 0.5 mm. The customer specification for the part is 10 mm. At 5%
significance level, what should the customer do?
A) State that the population mean is greater than 10 mm.
B) Change their specification to 9.5 mm.
C) Accept the lot.
D) Reject the lot.
ANSWER
D
t-value = (9.5 − 10)/(0.5 /sq. rt (20)) = -4.472 t-critical = t(0.025, 19) = - 2.093 (from t-table)
t-value = -4.472 < t-critical = -2.093. Reject the null hypothesis, meaning the lot mean is
not the same as the target or customer specification. The customer should reject the lot.
Question 4
Lean originated from:
GE.
Ford.
Toyota.
Motorola.
ANSWER
Toyota
2
,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."
Question 5
What is the minimum number of sample items required to carry out a meaningful Attribute
Agreement Analysis?
10
30
50
15
ANSWER
50
It is recommended to have at least 50 sample items in Attribute Agreement Analysis to
establish appropriate results.
Question 6
We use Cook's distance statistics to identify unusual data points or observations that
A) have multicollinearity.
B) deviate from the normality conditions.
C) influence the regression fit significantly.
D) Are equally spaced from the center.
3
, ANSWER
C
Cook's distance statistics is a measure of the distance between the fitted values calculated
with and without the ith observation. It is used to identify the unusual observations that
may have influence on the regression model.
Question 7
What is the advantage of using EWMA or CUSUM charts over conventional control charts?
Able to detect large process shifts
Easier in calculation
Very accurate
Able to detect small process shifts
ANSWER
Able to detect small process shifts
EWMA and CUSUM charts are able to detect any small shift (< 1.5 times sigma) in a
process, which is not possible with a conventional Shewhart control chart.
Question 8
T/F Mixed distributions form if data come from several sources that are expected to be the
same yet are not.
ANSWER
True
4
