OBHR 701 Midterm | Course Paper

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True or False: The principle of parsimony indicates that the simplest model that gets the

job done adequately should be used.

True or False: A regression had the following results: SST = 82.55, SSE = 29.85. It can

be said that 73.4% of the variation in the dependent variable is explained by the

independent variables in the regression.

True or False: TABLE 19-6

A student wanted to find out the optimal strategy to study for a Business Statistics

exam. He constructed the following payoff table based on the mean amount of time he

needed to study every week for the course and the degree of difficulty of the exam.

From the information that he gathered from students who had taken the course, he

concluded that there was a 40% probability that the exam would be easy.

Referring to Table 19-6, the optimal strategy using the expected monetary value

criterion is to study 8 hours per week on average for the exam.

True or False: TABLE 17-8

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), daily mean of the percentage of students

attending class (% Attendance), mean teacher salary in dollars (Salaries), and

instructional spending per pupil in dollars (Spending) of 47 schools in the state.

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

variable, X1 = % Attendance, X2 = Salaries and X3 = Spending:

Referring to Table 17-8, there is sufficient evidence that the daily mean of the

percentage of students attending class has an effect on the percentage of students

passing the proficiency test while holding constant the effect of all the other

independent variables at a 5% level of significance.

TABLE 11-5

A hotel chain has identically small sized resorts in 5 locations in different small islands.

The data that follow resulted from analyzing the hotel occupancies on randomly

selected days in the 5 locations.

Analysis of Variance

* or p < 0.005, tabular value

True or False: Referring to Table 11-5, if a level of significance of 0.05 is chosen, the

null hypothesis should be rejected.

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, we can conclude that, holding constant the effect of

the other independent variables, the number of years of education received has no

impact on the mean number of weeks a worker is unemployed due to a layoff at a 1%

level of significance if all we have is the information of the 95% confidence interval

estimate forÎ²2.

TABLE 12-5

Four surgical procedures currently are used to install pacemakers. If the patient does not

need to return for follow-up surgery, the operation is called a “clear” operation. A heart

center wants to compare the proportion of clear operations for the 4 procedures, and

collects the following numbers of patients from their own records:

They will use this information to test for a difference among the proportion of clear

operations using a chi-square test with a level of significance of 0.05.

True or False: Referring to Table 12-5, there is sufficient evidence to conclude that the

proportions between procedure A and procedure B are different at a 0.05 level of

significance.

True or False: A sample is used to obtain a 95% confidence interval for the mean of a

population. The confidence interval goes from 15 to 19. If the same sample had been

used to test the null hypothesis that the mean of the population is equal to 20 versus the

alternative hypothesis that the mean of the population differs from 20, the null

hypothesis could be accepted at a level of significance of 0.01.

True or False: TABLE 17-8

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), daily mean of the percentage of students

attending class (% Attendance), mean teacher salary in dollars (Salaries), and

instructional spending per pupil in dollars (Spending) of 47 schools in the state.

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

variable, X1 = % Attendance, X2 = Salaries and X3 = Spending:

Referring to Table 17-8, you can conclude that the mean teacher salary has no impact

on the mean percentage of students passing the proficiency test at a 5% level of

significance using the 95% confidence interval estimate for Î²2.

True or False: Referring to Table 14-16, the 0 to 60 miles per hour acceleration time of

a sedan is predicted to be 0.0005 seconds higher than that of a non-sedan with the same

engine size.

How many tissues should the Kimberly Clark Corporation package of Kleenex contain?

Researchers determined that 60 tissues is the mean number of tissues used during a

cold. Suppose a random sample of 100 Kleenex users yielded the following data on the

number of tissues used during a cold: = 52,

S = 22. Suppose the alternative you wanted to test was H1 : < 60. State the correct

rejection region for = 0.05.

A) Reject H0 if t > 1.6604.

B) Reject H0 if t < -1.6604.

C) Reject H0 if t > 1.9842 or Z < -1.9842.

D) Reject H0 if t < -1.9842.

Suppose the probability of a car accident taking place anywhere on a 20-mile stretch of

highway is the same. Which of the following distributions would you use to determine

the probability that a car accident will occur somewhere between the 5-mile and

15-mile posts of the highway?

A) Normal distribution

B) Poisson distribution

C) Uniform distribution

D) Exponential distribution

The fairly regular fluctuations that occur within each year would be contained in the

________ component.

A) trend

B) cyclical

C) irregular

D) seasonal

TABLE 18-1

A local newspaper has 10 delivery boys who each deliver the morning paper to 50

customers every day. The owner decides to record the number of papers delivered on

time for a 10-day period for one of the delivery boys and construct a p chart to see

whether the percentage is too erratic.

Referring to Table 18-1, what is the numerical value of the center line for the p chart?

A) 0.926

B) 0.911

C) 0.885

D) 0.500

If the outcomes of a variable follow a Poisson distribution, then their

A) mean equals the standard deviation.

B) median equals the standard deviation.

C) mean equals the variance.

D) median equals the variance.

TABLE 12-4

A computer used by a 24-hour banking service is supposed to randomly assign each

transaction to one of 5 memory locations. A check at the end of a day’s transactions

gave the counts shown in the table to each of the 5 memory locations, along with the

number of reported errors.

The bank manager wanted to test whether the proportion of errors in transactions

assigned to each of the 5 memory locations differ.

Referring to Table 12-4, the critical value of the test statistic at 1% level of significance

A) 7.7794.

B) 13.2767.

C) 20.0902.

D) 23.2093.

For sample sizes greater than 30, the sampling distribution of the mean will be

approximately normally distributed

A) regardless of the shape of the population.

B) only if the shape of the population is symmetrical.

C) only if the standard deviation of the samples are known.

D) only if the population is normally distributed.

TABLE 17-8

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), daily mean of the percentage of students

attending class (% Attendance), mean teacher salary in dollars (Salaries), and

instructional spending per pupil in dollars (Spending) of 47 schools in the state.

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

variable, X1 = % Attendance, X2 = Salaries and X3 = Spending:

Referring to Table 17-8, which of the following is the correct alternative hypothesis to

test whether instructional spending per pupil has any effect on the percentage of

students passing the proficiency test, taking into account the effect of all the other

independent variables?

A) H1 : Î²0 â‰ 0

B) H1 : Î²1 â‰ 0

C) H1 : Î²2 â‰ 0

D) H1 : Î²3 â‰ 0

Referring to Table 14-11, which of the following statements is

supported by the analysis shown?

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 affect 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 .t the interaction model:

Y = Î²0 + Î²1X1 + Î²2X2 + Î²3X1X2 + Îµ

Output from Microsoft Excel follows:

A) There is suffcient evidence (at Î± = 0.05) of curvature in the

relationship between weight loss (Y) and months on program (X1).

B) There is suffcient evidence (at Î± = 0.05) to indicate that the

relationship between weight loss (Y) and months on program (X1)

varies with session time.

C) There is insuffcient evidence (at Î± = 0.05) of curvature in the

relationship between weight loss (Y) and months on program (X1).

D) There is insuffcient evidence (at Î± = 0.05) to indicate that the

relationship between weight loss (Y) and months on program (X1)

varies with session time.

TABLE 17-2

One of the most common questions of prospective house buyers pertains to the cost of

heating in dollars (Y). To provide its customers with information on that matter, a large

real estate firm used the following 4 variables to predict heating costs: the daily

minimum outside temperature in degrees of Fahrenheit (X1), the amount of insulation in

inches (X2), the number of windows in the house (X3), and the age of the furnace in

years (X4). Given below are the EXCEL outputs of two regression models.

Referring to Table 17-2, what is the 90% confidence interval for the expected change in

heating costs as a result of a 1 degree Fahrenheit change in the daily minimum outside

temperature using Model 1?

A) [-6.58, -3.65]

B) [-6.24, -2.78]

C) [-5.94, -3.08]

D) [-2.37, 15.12]

TABLE 2-6

A sample of 200 students at a Big-Ten university was taken after the midterm to ask

them whether they went bar hopping the weekend before the midterm or spent the

weekend studying, and whether they did well or poorly on the midterm. The following

table contains the result.

Referring to Table 2-6, if the sample is a good representation of the population, we can

expect ________ percent of those who spent the weekend studying to do poorly on the

midterm.

A) 10

B) 20

C) 45

D) 50

TABLE 12-19

The director of the MBA program of a state university wanted to know if a one-week

orientation would change the proportion among potential incoming students who would

perceive the program as being good. Given below is the result from 215 students’ view

of the program before and after the orientation.

Referring to Table 12-19, which test should she use?

A) X2 test for difference in proportions

B) Z test for difference in proportions

C) McNemar test for difference in proportions

D) Wilcoxon rank sum test

TABLE 11-8

A physician and president of a Tampa Health Maintenance Organization (HMO) are

attempting to show the benefits of managed health care to an insurance company. The

physician believes that certain types of doctors are more cost-effective than others. One

theory is that Primary Specialty is an important factor in measuring the

cost-effectiveness of physicians. To investigate this, the president obtained independent

random samples of 20 HMO physicians from each of 4 primary specialties – General

Practice (GP), Internal Medicine (IM), Pediatrics (PED), and Family Physicians (FP) –

and recorded the total charges per member per month for each. A second factor which

the president believes influences total charges per member per month is whether the

doctor is a foreign or USA medical school graduate. The president theorizes that foreign

graduates will have higher mean charges than USA graduates. To investigate this, the

president also collected data on 20 foreign medical school graduates in each of the 4

primary specialty types described above. So information on charges for 40 doctors (20

foreign and 20 USA medical school graduates) was obtained for each of the 4

specialties. The results for the ANOVA are summarized in the following table.

Referring to Table 11-8, what degrees of freedom should be used to determine the

critical value of the F ratio against which to test for differences in the mean charges for

doctors among the four primary specialty areas?

A) numerator df = 1, denominator df = 159

B) numerator df = 3, denominator df = 159

C) numerator df = 1, denominator df = 152

D) numerator df = 3, denominator df = 152

TABLE 6-7

A company has 125 personal computers. The probability that any one of them will

require repair on a given day is 0.15.

Referring to Table 6-7 and assuming that the number of computers that requires repair

on a given day follows a binomial distribution, compute the probability that there will

be less than 8 computers that require repair on a given day using a normal

approximation.

TABLE 17-10