OBHR 343 Test 2 | Course Paper

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True or False: In a Poisson distribution, the mean and standard deviation are equal.

True or False: TABLE 17-10

Given below are results from the regression analysis where the dependent variable is

the number of weeks a worker is unemployed due to a layoff (Unemploy) and the

independent variables are the age of the worker (Age), the number of years of education

received (Edu), the number of years at the previous job (Job Yr), a dummy variable for

marital status (Married: 1 = married, 0 = otherwise), a dummy variable for head of

household (Head: 1 = yes, 0 = no) and a dummy variable for management position

(Manager: 1 = yes, 0 = no). We shall call this Model 1. The coefficient of partial

determination ( ) of each of the 6 predictors are, respectively,

0.2807, 0.0386, 0.0317, 0.0141, 0.0958, and 0.1201.

Model 2 is the regression analysis where the dependent variable is Unemploy and the

independent variables are Age and Manager. The results of the regression analysis are

given below:

Referring to Table 17-10, Model 1, there is sufficient evidence that being married or not

makes a difference in the mean number of weeks a worker is unemployed due to a

layoff while holding constant the effect of all the other independent variables at a 10%

level of significance.

TABLE 8-9

A university wanted to find out the percentage of students who felt comfortable

reporting cheating by their fellow students. A survey of 2,800 students was conducted

and the students were asked if they felt comfortable reporting cheating by their fellow

students. The results were 1,344 answered “Yes” and 1,456 answered “No.”

True or False: Referring to Table 8-9, a 90% confidence interval calculated from the

same data would be narrower than a 99% confidence interval.

TABLE 8-16

The president of a university is concerned that the percentage of students who have

cheated on an exam is higher than the 1% acceptable level. A confidential random

sample of 1,000 students from a population of 7,000 revealed that 6 of them said that

they had cheated on an exam during the last semester.

True or False: Referring to Table 8-16, the president can be 90% confident that no more

than 1% of the students at the university had cheated on an exam during the last

semester.

True or False: The squared difference between the observed and theoretical frequencies

should be large if there is no significant difference between the proportions.

True or False: TABLE 17-9

What are the factors that determine the acceleration time (in sec.) from 0 to 60 miles per

hour of a car? Data on the following variables for 171 different vehicle models were

collected:

Accel Time: Acceleration time in sec.

Cargo Vol: Cargo volume in cu. ft.

HP: Horsepower

MPG: Miles per gallon

SUV: 1 if the vehicle model is an SUV with Coupe as the base when SUV and Sedan

are both 0

Sedan: 1 if the vehicle model is a sedan with Coupe as the base when SUV and Sedan

are both 0

The regression results using acceleration time as the dependent variable and the

remaining variables as the independent variables are presented below.

The various residual plots are as shown below.

The coefficient of partial determination ( ) of each of the 5

predictors are, respectively, 0.0380, 0.4376, 0.0248, 0.0188, and 0.0312.

The coefficient of multiple determination for the regression model using each of the 5

variables Xj as the dependent variable and all other X variables as independent variables

( ) are, respectively, 0.7461, 0.5676, 0.6764, 0.8582, 0.6632.

Referring to Table 17-9, the errors (residuals) appear to be normally distributed.

True or False: The amount of bleach a machine pours into bottles has a mean of 36 oz.

with a standard deviation of 0.15 oz. Suppose we take a random sample of 36 bottles

filled by this machine. The sampling distribution of the sample mean has a mean of 36

oz.

TABLE 14-15

The superintendent of a school district wanted to predict the

percentage of students passing a sixth-grade proficiency test. She

obtained the data on percentage of students passing the proficiency

test (% Passing), mean teacher salary in thousands of dollars

(Salaries), and instructional spending per pupil in thousands of dollars

(Spending) of 47 schools in the state.

Following is the multiple regression output with Y = % Passing as the

dependent variable, X1 = Salaries and X2 = Spending:

True or False: Referring to Table 14-15, the null hypothesis H0 : Î²1 =

Î²2 = 0 implies that percentage of students passing the proficiency

test is not a.ected by either of the explanatory variables.

TABLE 13-10

The management of a chain electronic store would like to develop a model for

predicting the weekly sales (in thousands of dollars) for individual stores based on the

number of customers who made purchases. A random sample of 12 stores yields the

following results:

True or False: Referring to Table 13-10, the mean weekly sales will increase by an

estimated $10 for each additional purchasing customer.

TABLE 8-15

The president of a university is concerned that illicit drug use on campus is higher than

the 5% targeted level. A random sample of 250 students from a population of 2,000

revealed that 7 of them had used illicit drugs during the last 12 months.

True or False: Referring to Table 8-15, using the 90% one-sided confidence interval, the

president can be 95% confident that no more than 5% of the students at the university

had used illicit drugs during the last 12 months.

True or False: The larger the p-value, the more likely you are to reject the null

hypothesis.

Referring to Table 14-18, which of the following is the correct

expression for the estimated model?

TABLE 14-18

A logistic regression model was estimated in order to predict the

probability that a randomly chosen university or college would be a

private university using information on mean total Scholastic Aptitude

Test score (SAT) at the university or college and whether the TOEFL

criterion is at least 90 (Toe90 = 1 if yes, 0 otherwise). The

dependent variable, Y, is school type (Type = 1 if private and 0

otherwise).

The PHStat output is given below:

A) Y = -3.9594 + 0.0028 SAT + 0.1928 Toe90

B) = -3.9594 + 0.0028 SAT + 0.1928 Toe90

C) ln (odds ratio) = -3.9594 + 0.0028 SAT + 0.1928 Toe90

D) ln (estimated odds ratio) = -3.9594 + 0.0028 SAT + 0.1928

Toe90

The head librarian at the Library of Congress has asked her assistant for an interval

estimate of the mean number of books checked out each day. The assistant provides the

following interval estimate: from 740 to 920 books per day. What is an efficient,

unbiased point estimate of the number of books checked out each day at the Library of

Congress?

A) 740

B) 830

C) 920

D) 1,660

As an aid to the establishment of personnel requirements, the director of a hospital

wishes to estimate the mean number of people who are admitted to the emergency room

during a 24-hour period. The director randomly selects 64 different 24-hour periods and

determines the number of admissions for each. For this sample, = 396 and S = 100.

Which of the following assumptions is necessary in order for a confidence interval to be

valid?

A) The population sampled from has an approximate normal distribution.

B) The population sampled from has an approximate t distribution.

C) The mean of the sample equals the mean of the population.

D) None of these assumptions are necessary.

The coefficient of multiple determination

A) measures the variation around the predicted regression equation.

B) measures the proportion of variation in Y that is explained by X1 and X2.

C) measures the proportion of variation in Y that is explained by X1 holding X2

constant.

D) will have the same sign as b1.

An insurance company evaluates many variables about a person before deciding on an

appropriate rate for automobile insurance. A representative from a local insurance

agency selected a random sample of 15 insured drivers and recorded the amount of

claims each made in the last 3 years. Based on this information, which of the following

will you construct to learn about the mean amount of claims made by the company’s

customer?

A) Confidence interval estimate for the mean using the standard normal distribution

B) Confidence interval estimate for the mean using the Student’s t distribution

C) Confidence interval estimate for the proportion using the standard normal

distribution

D) Confidence interval estimate for the difference between two means using the

standard normal distribution

A certain type of rare gem serves as a status symbol for many of its owners. In theory,

for low prices, the demand increases and it decreases as the price of the gem increases.

However, experts hypothesize that when the gem is valued at very high prices, the

demand increases with price due to the status owners believe they gain in obtaining the

gem. Data on price and quantity sold were collected for a sample of 35 rare gems of this

type. Which of the following would be the most appropriate analysis to perform?

A) Quadratic regression model

B) Exponential smoothing

C) Autoregressive modeling for trend fitting and forecasting

D) Least-squares forecasting with monthly or quarterly data

An airline wants to select a computer software package for its reservation system. Four

software packages (1, 2, 3, and 4) are commercially available. The airline will choose

the package that bumps as few passengers, on the average, as possible during a month.

An experiment is set up in which each package is used to make reservations for 5

randomly selected weeks. (A total of 20 weeks was included in the experiment.) Which

of the following tests will be the most appropriate?

A) Paired t test

B) Wilcoxon rank sum test

C) McNemar test

D) Tukey-Kramer multiple comparisons procedure for one-way ANOVA

TABLE 11-7

A campus researcher wanted to investigate the factors that affect visitor travel time in a

complex, multilevel building on campus. Specifically, he wanted to determine whether

different building signs (building maps versus wall signage) affect the total amount of

time visitors require to reach their destination and whether that time depends on

whether the starting location is inside or outside the building. Three subjects were

assigned to each of the combinations of signs and starting locations, and travel time in

seconds from beginning to destination was recorded. An Excel output of the appropriate

analysis is given below:

ANOVA

Referring to Table 11-7, the degrees of freedom for the different building signs (factor

A) is

A) 1.

B) 2.

C) 3.

D) 8.

TABLE 13-2

A candy bar manufacturer is interested in trying to estimate how sales are influenced by

the price of their product. To do this, the company randomly chooses 6 small cities and

offers the candy bar at different prices. Using candy bar sales as the dependent variable,

the company will conduct a simple linear regression on the data below:

Referring to Table 13-2, to test whether a change in price will have any impact on sales,

what would be the critical values? Use = 0.05.

A) 2.5706

B) 2.7765

C) 3.1634

D) 3.4954

An airline wants to select a computer software package for its reservation system. Four

software packages (1, 2, 3, and 4) are commercially available. An experiment is set up

in which each package is used to make reservations for 5 randomly selected weeks and

data on the number of passengers that are bumped over a month are collected. (A total

of 20 weeks was included in the experiment.) The variability of the number of

passengers that are bumped is found to be roughly the same for the 4 packages. The

distribution on the number of passengers that are bumped has been found out to be

right-skewed for package 1 and 4, left-skewed for package 2 and normal for package 3.

Which of the following tests will be the most appropriate to find out if the mean

number of passengers being bumped over a month is the same across the 4 packages?

A) Paired t test

B) Pooled-variance t test

C) One-way ANOVA F test for differences among more than two means

D) Kruskal-Wallis rank test

TABLE 18-3

A quality control analyst for a light bulb manufacturer is concerned that the time it takes

to produce a batch of light bulbs is too erratic. Accordingly, the analyst randomly

surveys 10 production periods each day for 14 days and records the sample mean and

range for each day.

Referring to Table 18-3, suppose the analyst constructs an chart to see if the

production process is in-control. What is the upper control limit (UCL) for this chart?

A) 62.15

B) 60.95

C) 59.85

D) 58.75

True or False: Faculty rank (professor to lecturer) is an example of discrete numerical

data.

Which of the following yields a simple random sample?

A) All students in a class are divided into groups of 15. One student is randomly chosen

from the 1st group, the remaining observations are every 15th student thereafter.

B) The best 15 students, according to the opinion of the instructor, in a class are

selected.

C) The names of 50 students in a class are written on 50 different pieces of paper and

put in a hat. The first 15 pieces of paper are selected blindly one at a time without

replacing them back in the hat after shuffling the papers thoroughly.

D) All students in a class are divided into groups according to the rows that they are

seated. One of the groups is randomly selected.

Referring to Table 14-11, what null hypothesis would you test to

determine whether the slope of the linear relationship between

weight loss (Y) and time on the program (X1) varies according to time

of session?

TABLE 14-11

A weight-loss clinic wants to use regression analysis to build a model

for weight loss of a client (measured in pounds). Two variables

thought to a.ect weight loss are client’s length of time on the

weight-loss program and time of session. These variables are

described below:

Y = Weight loss (in pounds)

X1 = Length of time in weight-loss program (in months)

X2 = 1 if morning session, 0 if not

Data for 25 clients on a weight-loss program at the clinic were

collected and used to fit the interaction model:

Y = Î²0 + Î²1X1 + Î²2X2 + Î²3X1X2 + Îµ

Output from Microsoft Excel follows:

A) H0 : Î²1 = 0

B) H0 : Î²2 = 0

C) H0 : Î²3 = 0

D) H0 : Î²1 = Î²2 = 0

True or False: Student grades (A to F) are an example of continuous numerical data.

TABLE 17-10