QBA 121 Managerial Statistics II Fall 2015
Regression Diagnostics  Solutions
Linear Regression Regression Diagnostics Solutions
Objectives:
1. Understand the different types of suspect points
2. Understand the impact of suspect points on a regression.
3.
QBA 121 Managerial Statistics II Fall 2015 Solutions
Multiple Linear Regression: Time Series & Autocorrelation
Solutions
When we collect data over time (daily, weekly, etc.) we are concerned about autocorrelation.
Autocorrelation occurs when: the regress
QBA 121 Managerial Statistics II Fall 2015 Solutions
MLR: Businessweek Rankings Solution
The general theoretical model for Multiple Linear Regression (MLR) takes the form:
=
y 0 + 1 x1 + 2 x2 + + k xk +
Where y is the dependent variable; x1 , x 2 ,., x k
QBA 121 Managerial Statistics II Fall 2015 Solutions
Multiple Linear Regression: Model Building Solutions
Objectives:
1.
Review the various methods we evaluate a regression model
2.
Understand when to develop a nonlinear model and how to develop these mo
QBA 121 Managerial Statistics II Fall 2015 Solutions
MLR: Model Building Functional Forms Solutions
Objectives:
1. Understand why the logarithmic transformation is frequently used for economic data, which
is frequently rightskewed
2. Understand the homos
QBA 121 Managerial Statistics II Fall 2015 Solutions
Higherorder models and Interactions Solutions
Objectives:
1. Use MLR to develop a quadratic model with interaction terms for continuous variables.
2. An introduction to inventory questions, which frequ
QBA 121 Managerial Statistics II Fall 2015
Regression Diagnostics Exercise Solution
Regression Diagnostics Exercise Solution
Objectives:
1. Evaluate residuals in Simple Linear Regression.
2. Apply the equations for different types of suspect points in Exc
Instructions
a. You have 1 hour and 20 minutes to complete this exam.
b. You can use your notes, tables, and calculator while taking this test.
c. Show all of your work clearly (without skipping steps) to obtain maximum credit. If
appropriate, draw figure
QBA 121 Fall 2015 Quiz 2 Abridged Solution
Quiz #2 Simple Linear Regression Abridged Solution
Instructions:
You may use 3 handwritten cheat sheets (both sides), statistical tables, and a calculator
If you cannot answer part of a question, and a subsequent
Name: QBA 120 Quiz 1
Table: Twenty WellPaid CEOs
Column 2 Column 3 Column 4 Column 5 Column 6
Column1
Salary
m
w
um 57
47
MBA
Bachelors
HE
W

mm m
"um
um
nil
Marijn E Dekkers Thenno Fisher
Michael D Watford
1.
Researchers at Dow Chemical Co. investigated the effect of tablet surfacearea to
volume ratio on the rate at which a drug is released in a controlledrelease dosage.
Six similarly shaped tablets were prepared with different weights and thicknesses,
an
1. Private colleges and universities rely on money contributed by individuals and
corporations for their operating expenses. Much of this money is put into a
fund called an endowment, and the school spends only the interest earned by
the fund. A recent su
First Name: Last Name:
1. State True or False: lndicate your answer by circling only one choice.
A value of zero for the coefcient of correlation (r) implies that x and y are
unrelated. (2 Points)
r
A.) True < B.) False )
2. A sales manager was interested
First Name: Last Name:
1. A value of zero for the coefcient of correlation (r) implies that x and y are linearly
unrelat d. (2 Points) \aho 51'
l'l'H of no linear Ya 5 P
:5.) lrue) B.) False I e I'S Potrws
2. The managers of a brokerage rm are interested
First Name: Last Name:
1. A 95% condence interval for the average salary of all CEOs in the electronics
industry was constructed using the results of a random survey of 45 CEOs. The
interval was ($97911, $110014). Which of the following will result in a r
1. Steps in Hypothesis Testing (2 Points)
a. Alternate Hypothesis 1
b. Decision 1,
0. Test Statistics 1.
d. Significance Level 3
e. Conclusion '1
f.
g.
Null Hypothesis \
x \ e s
Rejection Region/Critical Region H163 6" 0 Rd
Select the choice that arrange
1. State True or False: Indicate your answer by circling only one choice.
A value of zero for the coefcient of correlation (r) implies that x and y are
unrelated. (2 Points)
A.) True B.) False
2. To investigate the relationship between yield of potatoes,
First Name: Last Name:
1. State True or False: Indicate your answer by circling only one choice.
A value of zero for the coefficient of correlation (r) implies that x and y are linearly
Wd. (2 Points)
B.) False
2. A sales manager was interested in determi
1. A realtor wants to compare the mean salestoappraisal ratios of residential
properties sold in four neighborhoods (A, B, C, and D). Four properties are
randomly selected from each neighborhood and the raEWrded for each, as
shown below. 214
A: 1.2,1.1,
1. State True or False:
Other things being equal, the condence interval for the mean will be wider for
95% condence than for 90% condence. (1 Point)
M
Hue.
2. The head librarian at the Library of Congress has asked her assistant for an
interval estimate o
1. State True or False: Indicate your answer by circling only one choice.
A value of zero for the coefcient of correlation (r) implies that x and y are linearly
unrlated. (2 Points)
B.) False
2. To investigate the relationship between yield of potatoes, y
1. The data below represent the amount of grams of carbohydrates in a serving of
breakfast cereal in a sample of 11 different servings.
1115 23 2919 22 212015 2517
a. Based on this sample, what is the average amount of grams of carbohydrates in
a serving
1. Each year advertisers spend billions of dollars purchasing commercial time on
television network. In the rst 6 months of one year, advertisers spent $1.1 billion.
In a recent article, the top 10 leading spenders and how much each spent (in million
of d
QBA 120 Exam l Fall 2014
Instructions
3. Read the instructions on this page but do not look at any other page until the
b.
proctor asks you to start.
Unless you have a special accommodation, you have about 1 hour and 20 minutes
to complete the following e
1. A machine is set to pump cleanser into a process at the rate of 10 gallons per
minute. Upon inspection, it is learned that the machine actually pumps cleanser at a
rate described by the uniform distribution over the interval 9.5 to 12.5 gallons per
min
Instructions
a. You have one class period (1 hour 20 minutes) to complete the following exam.
b. You can use your notes, book, and laptop while taking this test. However, going
on the internet is prohibited.
c. Show all of your work clearly (without skipp
QBA 120  Exam 1  Spring 2015
instructions
a. Read the instructions on this page but do not look at any other page until the
proctor announces the start of the quiz/exam.
b. Unless you have a special accommodation, you have about 1 hour and 20 minutes
to
QBA 120 Final Exam  Spring 2015
Instructions
. Read the instructions on this page but do not look at any other page until the
proctor announces the start of the quiz/exam.
. Unless you have a special accommodation. you have about 2 hours to complete
the
1. Suppose the time it takes for customer representatives to diagnose and x computer
problems is uniformly distributed from 10 to 120 minutes.
a. What is the probability that a problem is diagnosed and xed within 30 minutes?
(6 Points)
Note: Dene the nota