Chapter 11-13 Practice Test
Name________________________
Part I: Multiple Choice (Questions 1-10) - Circle the answer of your choice.
1.
Which one of the following is not a principle of experimentation?
(A)
(B)
Randomly allocating experimental units to treatments.
Stratifying the experimental units into groups of similar individuals and applying different
treatments to each stratum.
Using double blindness to eliminate bias.
Replicating to measure overall experimental error and increase precision.
Using a control group to determine whether treatment really works.
(C)
(D)
(E)
B; stratifying is for sampling and ‘applying different treatments to each stratum’ is incorrect.
2.
A simple random sample of size n is selected in such a way that
(A)
(B)
(C)
(D)
(E)
Each member of the population has an equal chance of being selected.
Each member of the population is given an opportunity to respond to the survey.
All samples of size n have the same chance of being selected.
The probability of selecting any sample is known to be 7  rand .
The sample is guaranteed to represent the entire population.
C; by definition.
3.
In sample surveys, bias can be controlled by all of the following except
(A)
(B)
(C)
(D)
(E)
Using a probability or chance sampling procedure.
Wording questions so they are not confusing or misleading.
Carefully training and supervising interviewers.
Prompting respondents so that they give correct responses.
Reducing non-response and under-coverage.
D; this introduces response bias.
4.
A graduate student conducts a study to determine whether a new activity-based method is better
than the traditional lecture of teaching statistics. He found two teachers to help him in his study
for one semester. Mr. Dull volunteered to continue teaching with traditional lectures and Ms.
Perky agreed to try the new activity-based method. Each teacher planned to teach two sections of
approximately forty students each for adequate replication. At the end of the semester, all
sections would take the same final exam and their scores would be compared. What is the
treatment variable in this study?
(A)
(B)
(C)
(D)
(E)
Teacher
Section of the Course
Teaching Method
Final Exam Score
Student
C; the method of instruction is being manipulated (traditional lecture vs. activity-based).
5.
In a study on the effect of reinforcement on learning from programmed text, two experimental
treatments are planned: reinforcement given after every frame of programmed text or
reinforcement given after every three frames. Which one of the following control groups would
serve best in this study?
(A)
(B)
(C)
(D)
(E)
A group which does not read the programmed text material.
A group that reads the programmed material in prose formats.
A group which reads the programmed material but does not receive reinforcement.
A group that reads the programmed text material and reinforcement is given at random.
A group which watches the video of the programmed material.
C;
6.
We say that the design of a study is biased if which of the following is true?
(A)
(B)
(C)
(D)
(E)
A racial or sexual preference is suspected.
Random placebos have been used.
The research designer has received a grant from a special interest group.
The correlation if greater than 1 or less than –1.
Certain outcomes are systematically favored.
E; by definition.
7.
Which of the following are true statements?
I.
II.
III.
(A)
(B)
(C)
(D)
(E)
Voluntary response samples often underrepresent people with strong opinions.
Convenience samples often lead to undercoverage bias.
Questionnaires with nonneutral wording are likely to have response bias.
I and II
I and III
II and III
I, II, and III
None of the above gives the true set of responses.
C; I is false because typically people with strong opinion are overrepresented in voluntary response
samples. II and III are true.
8.
To survey the opinions of bleacher fans at Wrigley Field, a surveyor plans to select every onehundredth fan entering the bleachers one afternoon. Which type of sampling method is being
used in this scenario?
(A)
(B)
(C)
(D)
(E)
Cluster Sampling
Stratified Sampling
Multistage Sampling
Simple Random Sampling
Systematic Sampling
E; they are selecting every 100th fan.
9.
What fault do all these sampling designs have in common?
I.
II.
III.
(A)
(B)
(C)
(D)
(E)
The Wall Street Journal plans to make a prediction for a presidential election based
on a survey of its readers.
A radio talk show asks people to phone in their views on whether the United States
should pay off its huge debt to China.
A police detective is interested in determining a sample of high school students and
interviews each one about any illegal drug use by the student during the past year.
All the designs make improper use of stratification.
All the designs have errors that can lead to strong bias.
All the designs confuse association with cause and effect.
None of the designs satisfactorily controls for sampling error.
None of the designs makes use of chance in selecting a sample.
B; I is a convenience sample, II is a voluntary response sample, and for III the design of the sample
might lead to response bias.
10.
The following students are available to serve on the Student Procrastination Committee.
1. Ally
4. Donald
7. Gina
10. Jan
13. Morris
16. Patti
2. Benji
5. Eli
8. Hank
11. Kyle
14. Norm
17. Quasimodo
3. Chad
6. Frannie
9. Ivana
12. Lana
15. Olive
18. Ramone
Using the randInt function your TI-83, select a simple random sample size 4. Before you select
your sample, seed your random number generator by storing 7 into rand ( 7  rand ). The
students who were selected were:
(A)
(B)
(C)
(D)
(E)
B;
Ally, Ramone, Kyle, Olive
Donald, Ramone, Kyle, Frannie
Jan, Kyle, Kyle, Ramone
Gina, Ivana, Patti, Eli
Norm, Donald, Morris, Frannie
Part II: Free Response (Questions 11-13) – Show your work and explain your results clearly.
11.
P.P. Pumpkineater, the renowned agricultural geneticist, has
mutated previous varieties of pumpkins and produced two
new strains, ScaryFace and CandleBreath. Because he has
limited marketing funds, he must decide which strain is the
most “jack-o-lanternable”. Having been in the jack-o-lantern
business for a long period of time, he has developed the
PPPJOL Test to compare different strains. The plot of land
available for planting is on the side of a hill with a large
number of trees on top and a stream near the bottom. He is
quite concerned about the effects of sunlight and water on the growth of the pumpkins. He has 60
seeds of each variety available for testing. Design an experiment that will help P.P. determine
which strain to market.
12.
At the recently opened theme park, Six Samples Over a Population, a carnival game allows a
player three attempts, using a dart, to pop a balloon. As soon as the player pops the balloon, he
wins the prize and the game is over. If he does not pop the balloon after the third attempt he
loses. John Bell, an avid dart-throwing balloon popper, estimates his probability of popping the
balloon on the first attempt at 20%, popping the balloon on the second attempt at 30%, and
popping the balloon on the third attempt at 40%. By describing an appropriate random digit
assignment and performing 10 simulations using the given random number table, determine the
probability that John wins the prize.
08424
44753
77377
28744
75592
08563
79140
92454
53645
66812
61421
47836
12609
15373
98481
14592
Let 0-1 win a prize on the 1st throw and 2-9 not win a prize.
Let 0-2 win a prize on the 2nd throw and 3-9 not win a prize.
Let 0-3 win a prize on the 3st throw and 4-9 not win a prize.
Stop after a prize is won or 3 attempts have been made.
Trial Number
1
2
3
4
5
6
7
8
9
10
Random Numbers
0
842
444
753
773
772
874
475
592
0
Outcome
prize
prize
no prize
prize
prize
prize
no prize
no prize
prize
prize
7
 .7 ; according to the simulation, the estimated probability of winning a prize is about 70%.
10
13.
A corporation employs 2000 male and 500 female engineers. A stratified random sample of 200
male and 50 female engineers gives each engineer 1 chance in 10 to be chosen. This sample
design gives every individual in the population the same chance to be chosen for the sample.
(a)
Is it an SRS? Explain your answer.
No, each group of 250 does not have the same chance of being selected.
(b)
Use the Random Number Table to select the first 5 female engineers to be in the sample.
Describe your method clearly.
60940
72024
17868
24943
61790
90656
87964
94359
18883
36009
19365
15412
39638
85453
46816
74025
Let 001-500 be a female engineer, and 000 and 501-999 not be a female.
The first 5 groups of 3 random digits in the appropriate range are 407, 202, 249, 179, and 090. These
would represent 5 female engineers.
(c)
Suppose that the corporation is concerned with worker satisfaction. They decide to conduct a
survey of the engineers. The results of the findings indicated that “a survey of 2500 engineers
found that while most employees continue to find their jobs interesting, and are even satisfied
with their commutes, a bare majority like their jobs.” This statement was based on the fact that
only 51 percent of those responding to the survey indicated that they were satisfied with their
jobs. The survey was conducted by mail. Describe any potential sources of bias that you think
might limit the ability to draw conclusions about engineers working at this corporation based on
the data collected in this survey.
Any survey conducted by mail is subject to selection bias (our text calls this undercoverage) because
anyone without an address is excluded – some of the engineers may be temporarily staying with a host
family/friend or in a hotel).
Nonresponse bias could also an issue if the engineers that did not reply differ in some way from the
those that did reply.
Response bias could be an issue if the engineers felt that their responses might not be confidential (and
could possibly be used against them).