EBK BASIC BUSINESS STATISTICS
14th Edition
ISBN: 9780134685090
Author: STEPHAN
Publisher: VST
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Textbook Question
Chapter 8, Problem 66PS
Call centers today play an important role in managing day-to-day business communications with customers. It’s important, therefore, to monitor a comprehensive set of metrics, which can help business understand the overall performance of a call center. One key metric for measuring overall call center performance is service level which is defined as the percentage of calls answered by a human agent within a specified number of seconds. The file ServiceLevel contains the following data for time, in seconds, to answer 50 incoming calls to a financial service call center:
a. Construct a
b. What assumption do you need to make about the population to construct the interval in (a)?
c. Given the data presented, do you think the assumption needed in (a) is valid? Explain.
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Students have asked these similar questions
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+
++
Table 2: Crack Experiment for Exercise 2
A B C D Treatment Combination
(1)
Replicate
I II
7.037
6.376
14.707 15.219
|++++ 1
བྱ॰༤༠སྦྱོ སྦྱོཋཏྟཱུ
a
b
ab
11.635 12.089
17.273 17.815
с
ас
10.403 10.151
4.368 4.098
bc
abc
9.360 9.253
13.440 12.923
d
8.561 8.951
ad
16.867 17.052
bd
13.876 13.658
abd
19.824 19.639
cd
11.846 12.337
acd
6.125
5.904
bcd
11.190 10.935
abcd
15.653 15.053
Question 3
Continuation of Exercise 2. One of the variables in the experiment described in Exercise 2, heat treatment
method (C), is a categorical variable. Assume that the remaining factors are continuous.
(a) Write two regression models for predicting crack length, one for each level of the heat treatment method
variable. What differences, if any, do you notice in these two equations?
(b) Generate appropriate response surface contour plots for the two regression models in part (a).
(c) What set of conditions would you recommend for the factors A, B, and D if you use heat treatment method
C = +?
(d) Repeat…
Question 2
A nickel-titanium alloy is used to make components for jet turbine aircraft engines. Cracking is a potentially
serious problem in the final part because it can lead to nonrecoverable failure. A test is run at the parts producer
to determine the effect of four factors on cracks. The four factors are: pouring temperature (A), titanium content
(B), heat treatment method (C), amount of grain refiner used (D). Two replicates of a 24 design are run, and
the length of crack (in mm x10-2) induced in a sample coupon subjected to a standard test is measured. The
data are shown in Table 2.
1
(a) Estimate the factor effects. Which factor effects appear to be large?
(b) Conduct an analysis of variance. Do any of the factors affect cracking? Use a = 0.05.
(c) Write down a regression model that can be used to predict crack length as a function of the significant
main effects and interactions you have identified in part (b).
(d) Analyze the residuals from this experiment.
(e) Is there an…
A 24-1 design has been used to investigate the effect of four factors on the resistivity of a silicon wafer. The data
from this experiment are shown in Table 4.
Table 4: Resistivity Experiment for Exercise 5
Run
A
B
с
D
Resistivity
1
23
2
3
4
5
6
7
8
9
10
11
12
I+I+I+I+Oooo
0
0
||++TI++o000
33.2
4.6
31.2
9.6
40.6
162.4
39.4
158.6
63.4
62.6
58.7
0
0
60.9
3
(a) Estimate the factor effects. Plot the effect estimates on a normal probability scale.
(b) Identify a tentative model for this process. Fit the model and test for curvature.
(c) Plot the residuals from the model in part (b) versus the predicted resistivity. Is there any indication on
this plot of model inadequacy?
(d) Construct a normal probability plot of the residuals. Is there any reason to doubt the validity of the
normality assumption?
Chapter 8 Solutions
EBK BASIC BUSINESS STATISTICS
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Ch. 8 - If X=75,S=24,andn=36, and assuming that the...Ch. 8 - Determine the critical value of t in each of the...Ch. 8 - Assuming that the populations is normally...Ch. 8 - Assuming that the population is normally...Ch. 8 - A marketing researcher wants to estimate the mean...Ch. 8 - A survey of nonprofit organizations showed that...Ch. 8 - The U.S. Department of Transportation requires...Ch. 8 - The file FastFood contains the amount that a...Ch. 8 - The file AirportRating contains the rating of...Ch. 8 - The annual NFL Super Bowl is the most widely...Ch. 8 - Is there a difference in the yields of different...Ch. 8 - One of the major measures of the quality of...Ch. 8 - A manufacturing company produces electric...Ch. 8 - The file MobileCommerce contains mobile commerce...Ch. 8 - One operation of a mill is cut pieces of steel...Ch. 8 - Ifn=200andX=50, Construct a 95 confidence interval...Ch. 8 - ifn=400andX=25, Construct a 99 confidence interval...Ch. 8 - A cellphone provider has the business objective of...Ch. 8 - In a survey of 1,003 adults concerning complaints...Ch. 8 - What do you value most when shopping in a retail...Ch. 8 - In a survey of 823 human resource professionals...Ch. 8 - A Pew Research Center survey of 4,787 adults found...Ch. 8 - What business, economic, policy and environmental...Ch. 8 - If you want to be 95 confident of estimating the...Ch. 8 - If you want to be 99 confident of estimating of...Ch. 8 - If you want to be 99 confident of estimating the...Ch. 8 - If you want to be 95 confident of estimating the...Ch. 8 - A survey is planned to determine the mean annual...Ch. 8 - If the manager of a bottled water distributor...Ch. 8 - If a light bulb manufacturing company wants to...Ch. 8 - If the inspection division of a county weights and...Ch. 8 - An advertising media analyst wants to estimate the...Ch. 8 - An advertising media analyst wants to estimate the...Ch. 8 - A growing niche in the restaurant business is...Ch. 8 - What does brand loyalty mean to consumers?...Ch. 8 - A Federal Reserve Bank of Atlanta report looks at...Ch. 8 - In a study of 443 nonprofits nationwide, 130...Ch. 8 - Cybersecurity is a critical business issue that...Ch. 8 - Personal data is the new currency of the digital...Ch. 8 - Why can you never really have 100 confidence of...Ch. 8 - When should you use the t distribution to develop...Ch. 8 - Why is it true that for a given sample size, n an...Ch. 8 - Why is the sample size needed to determine the...Ch. 8 - GlobalWablndex study noted the percentage of...Ch. 8 - How do smartphone owners use their smartphones...Ch. 8 - A market researcher for a consumer electronics...Ch. 8 - An information technology (IT) provider of cloud...Ch. 8 - The human resource (HR) director of a large...Ch. 8 - A national association devoted to HR and workplace...Ch. 8 - The financial impact of IT system downtime is a...Ch. 8 - The branch manager of an outlet (Store 1) of a...Ch. 8 - Scarlett and Heather, the owners of an upscale...Ch. 8 - The manufacturer of Ice Melt claims that its...Ch. 8 - Claims fraud (illegitimate claims) and buildup...Ch. 8 - A quality characteristic of interest for a...Ch. 8 - Call centers today play an important role in...Ch. 8 - The manufacturer of Boston and Vermont asphalt...Ch. 8 - The manufacturer of Boston and Vermont asphalt...Ch. 8 - Referring to the results in Problem 8.66...
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