Chapter 5 ­ Samples, Experiments, and Simulations ­ Review Game
Round 1 ­ DO NOT WRITE ON THIS PAPER.
1) A manufacturer wants to test a sample of the products his company produces. Products are produced in
sets of 100, and each set of 100 is called a lot. The company produces hundreds of lots each day. The
manufacturer decides to randomly select five lots from each day’s production run and test every product in
these five lots. Which of the following best describes this type of sampling?
a) Cluster
b) Stratified Random
c) Convenience
d) Systematic
e) Simple Random
2) For a large table of random numbers, which of the following is a correct statement?
a) The sequence 00 will not appear more than once.
b) Entries in one part of the table are independent of entries in another part.
c) A row of 40 digits will include each digit 0 through 9 exactly four times.
d) The sequence 05 will occur more than the sequence 15 since the sequence 05 represents both the two­digit
number 05 and the one­digit number 5.
e) The sequence 0123456789 is likely to occur in the first 1,000 digits.
3) When designing an experiment, why is it important to protect against confounding?
a) Confounding interferes with randomization.
b) Confounding increases the likelihood of bias.
c) Confounding makes it difficult to determine the actual cause of any observed change in the response
variable.
d) Confounding decreases the strength of the association between the explanatory variable and the response
variable.
e) Confounding makes it difficult to double blind an experiment.
4) Which of the following is NOT a valid reason for blocking when designing an experiment?
a) Blocking controls the effects of an outside variable by bringing that variable into the experiment to form the
blocks.
b) Blocking allows the researcher to isolate variability due to a factor other than the explanatory variable under
investigation.
c) Blocking can diminish confounding.
d) Blocking reduces the need for replication.
e) Blocking reduces variation.
5) A consumer products researcher wants to design an experiment testing the durability of two different types of
roofing tiles, brand X and brand Y. Ten test roofs are built, roofs 1 through 10, which will be subjected to
simulated weather in a controlled environment. Roofs 1 through 5 are covered with brand X tiles, and roofs 6
through 10 are covered with brand Y. One of the tile brands is exposed to cold and snow, and the other is
subjected to heat and rain, with the assignment made at random. After the simulation has ended, the water
resistance of the two types of tiles is compared. Which of the following is a valid observation of the experiment?
a) The experiment is well­planned and should serve its purpose.
b) The sample size of 10 is too small.
c) The treatments in the experiment are the tiles applied to the roofs.
d) Tile brands were randomly assigned to roofs.
e) There is a flaw in the design. Each brand of tile should be exposed to both sets of weather conditions.
6) Why is it possible to show cause­and­effect relationship between two variables using an experiment and not
an observational study?
a) Unlike observational studies, experiments can be double­blinded.
b) Unlike observational studies, experiments control for confounding variables.
c) Unlike observational studies, experiments can be blocked.
d) Experiments tend to be conducted with more care for details than observational studies.
e) Experiments tend to use larger sample sizes than observational studies.
Round 2 ­ DO NOT WRITE ON THIS PAPER.
7) A mattress manufacturer wants to test a new line of mattresses to see if a disturbance by a sleeper on one
side of a mattress will be noticeable to a sleeper on the other side. A random sample of 500 mattresses will be
used for the test. A house of cards is set up on one side of each mattress, and then a bowling ball is dropped
on the other side. This is done two more times, and the whole process is repeated with the sides switched. The
initial side assignments are selected at random for each mattress. A mattress is considered to be resistant to
disturbances if the house of cards collapses two times or fewer for the six trials on each mattress. The
manufacturer will find it acceptable if more than 80% of all mattresses are resistant to disturbances. Which of
the following best describes a shortcoming in the design of this study?
a) The sample size is insufficient.
b) The design will not permit mathematical calculations needed for statistical inference.
c) The measurements are subject to response bias.
d) Convenience sampling is used in the design.
e) The design lacks realism.
8) The editor of the newspaper at a large university wants to measure student opinion on a proposed change in
graduation requirements. The editor randomly selects 100 freshmen, 100 sophomores, 100 juniors, and 100
seniors to take a short survey. This plan is an example of what kinds of sampling?
a) Cluster sampling
b) Simple random sampling
c) Systematic sampling
d) Stratified random sampling
e) Convenience sampling
9) Which of these combinations is most effective at ensuring that the results of an experiment are not
confounded by the placebo effect?
a) Replication and blocking
b) Blocking and control
c) Control and blinding
d) Blinding and randomization
e) Randomization and replication
10) A certain high school has 2,350 students. The student body officers are interested in creating activities to
have freshmen become more involved. Which is the best method that will give the appropriate representation of
the freshmen at that school?
a) During the lunch hour, ask some freshmen their choice of activities.
b) Take a simple random sample of the entire student body and ask their choice of activities.
c) Take a simple random sample of the freshmen class only and ask their choice of activities.
d) Take a simple random sample of the non­freshmen and ask which activities they would have liked when they
were freshmen.
e) The student body officers should make the decision based on their experiences as freshmen.
11) What is the purpose of stratification in sampling?
a) To reduce variability in the response.
b) To increase the sample size.
c) To restrict which members of the population can be sampled.
d) To reduce response bias.
e) To ensure an equal probability of a particular individual being sampled.
12) Which of the following is NOT a result of a study’s design process?
a) Undercoverage
b) Voluntary response bias
c) Response bias
d) Sampling error
e) Nonresponse bias
Round 3 ­ DO NOT WRITE ON THIS PAPER.
13) A dentist has just returned from a dental convention where a new formula of toothpaste with additional
fluoride was announced. The maker of the toothpaste claims a reduction in cavities over the existing formula.
Before recommending this new toothpaste to her patients, the dentist decides to conduct an experiment of her
own. She asks 80 patients to volunteer to be part of the experiment. The experiment will last for 1 year.
a) Design the experiment that will allow the dentist to determine if the new formula reduces cavities as
compared to the old formula. Use complete sentences.
b) Explain “blinding” in the context of this situation and why it is important for the experiment.
ANSWERS
1) A
2) B
3) C
4) D
5) E
6) B
7) E
8) D
9) C
10) C
11) A
12) D
13) a) The 80 volunteers shall be randomly allocated into two groups of 40 (1). We will randomize by putting
names in a hat and the first name drawn is in the first group, the second name is in the second group, … (1)
One random group will use the old toothpaste exclusively. The other group will only use the new toothpaste (1).
After 1 year, the volunteers will be check and new cavities will be counted. Then, the number of new cavities for
each of the two groups will be compared (1).
b) Blinding in this context would be if the person brushing their teeth did not know which type of toothpaste they
were using. If the group using the new formula knew they had the new formula, they might eat healthier or brush
more carefully to help show that the formula works (2).