Question 1

Which statement is not true about randomized block designs?

Accepted Answer

A) Each block should have objects in all treatment and control groups. 
B) A block consists of objects that are similar on one or more variables. 
C) Blocks are randomly assigned to each of the treatment and control groups. 
D) All of the statements are true.

Question 2

Use the following information for following questions:. These two headlines are on the same topic.
Headline A: Children who view advertisements for fast food dramatically increase their risk of becoming
obese adolescents, a new study suggests.
Headline B: Viewing advertisements for fast food leads to childhood obesity, a new study finds.
-Was the study referenced most likely a controlled experiment or an observational study? Explain.

Accepted Answer

The answer of Use the following information for following questions:....

Question 3

Which of the following is not an important principle that should always be kept in mind when reading research articles containing statistical research results?

Accepted Answer

A) Don't rely solely on the conclusions of any single paper 
B) Be wary of conclusions based on very complex statistical or mathematical models. 
C) Stick to peer-reviewed journals. 
D) All of the above are important principles.

Question 4

A small study was conducted on a new procedure for treating atrial fibrillation. The study involved a new way to perform ablation surgery. One method currently being used had a success rate of only 50% in preventing additional episodes of atrial fibrillation within one year. The new method of performing ablation surgery was performed on 8 patients and 6 of the 8 patients did not suffer additional episodes of atrial fibrillation within one year. Choose the statement that best summarizes the significance of this result.

Accepted Answer

A) Many people would say that this result has both clinical and statistical significance because the probability of success increases from 50% to 75% and the result could have significant impact on
Lives. 
B) Although this result may have clinical significance, it does not have statistical significance because the sample size is so small. 
C) Although this result may have statistical significance, it does not have clinical significance because the sample size is so small. 
D) Although this result may have statistical significance, it does not have clinical significance because the sample was not randomly selected.

Question 5

Use the following information for following questions:. Often college students taking an
introductory course in psychology are required to participate in research experiments. One experiment
was performed to see if using colored paper increased reading comprehension. One hundred students
enrolled in an introductory college psychology course volunteered to participate in the study. Fifty of the
students were randomly chosen to read a chapter in a psychology test that was printed on yellow paper
and the remaining fifty students were given the same chapter to read printed on white paper. After
reading the chapter, each student was asked to answer a series of questions to test his/her comprehension.
The results indicated that those students reading the chapter printed on yellow paper tended to have higher
comprehension scores than those students reading the chapter printed on white paper.
-Choose the statement that correctly explains why we can or cannot make a cause-and-effect conclusion.

Accepted Answer

A) This was an observational study so we cannot conclude that reading comprehension increases when reading text printed on yellow paper. 
B) The participants were not selected from a larger population so we cannot conclude a cause-and- effect relationship. 
C) Since this was a controlled observational study, we can conclude there was a cause-and-effect relationship. 
D) This was an experimental study so we conclude that reading comprehension increases when reading from text printed on yellow paper, but the results cannot be generalized beyond the
Sample.

Question 6

A publisher is considering publishing a new magazine about environmentally-friendly living in the city and plans to gage interest in the magazine using potential consumers. Company researchers want to measure whether there is a difference in opinion between the new magazine and the competing publication. Company researchers believe that consumer reaction to the new magazine will depend on age so they decide to block on age. To do this, they create blocks for consumers between the ages 18-24 years, 25-32 years, 33-45 years, and 46 years and older. They then randomly select two of the blocks to read the first issue of the new magazine and the other two blocks to read a similar competing publication. Following the test, participants respond to a questionnaire about the magazine they read. Is this an effective design for the study? If not, describe an improvement.

Accepted Answer

The answer of A publisher is considering publishing a new...

Question 7

Suppose a sociologist is interested in finding out if there is an association between gender and opinions on human cloning. Which test design would be most appropriate for this scenario?

Accepted Answer

A) Two-sample t-test 
B) Chi-square 
C) Paired t-test 
D) ANOVA

Question 8

Which of the following is not a benefit of a stratified sampling plan?

Accepted Answer

A) Members of a stratum, or similar group, are likely to respond the same, which lead to results with lower variability. 
B) Increased precision 
C) Statistics from a stratum will reflect the parameters of the population as a whole. 
D) All of the above are benefits of a stratified sampling plan.

Question 9

Use the following information to answer questions (5) - (7). A tire manufacturer has made some
modifications to its most popular tire and wants to see if the tread on the modified tire will last
longer than the original tire. Because there is much variation in the way people drive, the
manufacturer decides to use blocking to reduce this variation. Twenty cars will be used to test the
tires. Ten cars are randomly selected to receive an original tire on the right rear wheel and a
modified tire on the left rear wheel. The remaining ten cars will receive an original tire on the left
rear wheel and a modified tire on the right rear wheel. Each car will then be driven 10,000 miles and
the amount of wear recorded for each wheel.
-Which test design would be most appropriate for this scenario?

Accepted Answer

A) Two-sample t-test 
B) Paired t-test 
C) Two-sample z-test 
D) Paired z-test

Question 10

Use the following information to answer questions (1) - (3). Scientists were interested in determining if
the amount of nicotine present in tobacco leaves is related to the amount of water received by the plants.
In a greenhouse, a total of 120 tobacco plants were selected. During the growing season, 30 plants were
randomly assigned to receive the normal amount of water, 30 plants received 75% of the normal amount
of water, 30 plants received 50% of the normal amount of water, and 30 plants received 25% of the
normal amount of water. At the end of the growing season, one leaf was selected at random from each
plant and the amount of nicotine present was recorded for each. Researchers determined that leaves from
tobacco plants receiving the normal amount of water during the growing season had more nicotine than
leaves from tobacco plants receiving less water.
-Was this an observational study or a controlled experiment?

Accepted Answer

A) Observational study because the plants were not a random sample. 
B) Observational study because the researchers determined how much water each group of plants would receive. 
C) Experimental because researchers determined, through randomized assignment, which plants belonged to which treatment group. 
D) Experimental because the researchers could not control the amount of nicotine in the plants.

Question 11

Use the following information to answer questions (5) - (7). A tire manufacturer has made some
modifications to its most popular tire and wants to see if the tread on the modified tire will last
longer than the original tire. Because there is much variation in the way people drive, the
manufacturer decides to use blocking to reduce this variation. Twenty cars will be used to test the
tires. Ten cars are randomly selected to receive an original tire on the right rear wheel and a
modified tire on the left rear wheel. The remaining ten cars will receive an original tire on the left
rear wheel and a modified tire on the right rear wheel. Each car will then be driven 10,000 miles and
the amount of wear recorded for each wheel.
-Is this a correct use of blocking?

Accepted Answer

A) Yes 
B) No

Question 12

Suppose a gumball manufacturer decides to inspect every twenty-fifth gumball for defects. What kind of sampling does this illustrate?

Accepted Answer

A) Systematic 
B) Stratified 
C) Cluster 
D) Random Sampling

Question 13

Which of the following is not a primary factor that affects the power of a test?

Accepted Answer

A) The size of the true difference between treatment groups 
B) Natural variability within the population 
C) The sample standard deviation 
D) Sample size

Question 14

Use the following information for following questions:. Which treatment is most effective at
treating carpet stains: vinegar, ammonia, or hydrogen peroxide? In a study, researchers randomly assigned
55 carpet samples with identical stains to one of three groups. Depending on which group they were
assigned to, each carpet sample received a home remedy of water mixed with vinegar, ammonia, or
hydrogen peroxide. Afterwards, each carpet sample was examined and any remaining stain was measured.
Researchers found that a vinegar and water mixture produced better results than both ammonia and
hydrogen peroxide.
-Was this a controlled experiment or an observational study?

Accepted Answer

A) Experimental because researchers determined, through randomized assignment, which treatment each carpet sample received 
B) Experimental because researchers could not determine how much of the stain was removed 
C) Observational study because researchers determined which treatment each carpet sample received 
D) Observational study because the carpet samples were not a random sample

Question 15

The city council of a moderate size city wants to gather input from the citizens of the city on the proposed expansion to the local airport. It has been decided that a stratified sampling plan would be the best way to get the desired information because opinions within the strata are likely to be similar. Which method of stratifying seems to be the most reasonable for this situation?

Accepted Answer

A) Stratify by gender. 
B) Stratify by age. 
C) Stratify by distance from the airport. 
D) Stratify by income.

Question 16

Which of the following statements is not true about a systematic sampling plan?

Accepted Answer

A) A systematic sampling plan divides the population into mini-populations that will have lower variability. 
B) With systematic sampling, objects from the population are sampled at regular intervals. 
C) Systematic sampling works best when objects are received in sequence during a specific time period and the characteristic of interest can be reasonably assumed to be randomly mixed during
The time period in which the data will be collected. 
D) All of the above statements are true for a systematic sampling plan.

Question 17

A coin collector has over 54 books containing varying number of coins of various denominations. He is very interested in knowing the value of the collection, but does not want to take the time to look up the value of each coin in the collection. He decides to randomly select 4 books and determines the value of each coin in each of the 4 books by looking up the coin in an online pricing book. What kind of sampling does this illustrate?

Accepted Answer

A) Systematic 
B) Stratified 
C) Cluster 
D) Random sampling

Question 18

Suppose the president of a large company is in the process of deciding whether to adopt a lunchtime exercise program.The purpose of the program is to improve the health of the employees and thus, reduce the medical expenses. To get more information, he instituted the exercise program for all the employees in one office. The president knows that during the winter months medical expenses are relatively high because of high occurrences of colds and flu. Therefore, he records the medical expenses of the employees in the

Accepted Answer

The answer of Suppose the president of a large company...

Question 19

Use the following information for following questions:. These two headlines are on the same topic.
Headline A: Children who view advertisements for fast food dramatically increase their risk of becoming
obese adolescents, a new study suggests.
Headline B: Viewing advertisements for fast food leads to childhood obesity, a new study finds.
-Which one has language that suggests a cause- and effect relationship? Is this problematic? Can you think of a confounding factor other than exposure to fast food advertisements that might cause childhood obesity?

Accepted Answer

The answer of Use the following information for following questions:....

Question 20

A study is to be undertaken to determine the teacher workload in the public schools in a large county in California. The target population is all high school teachers (grades 9 - 12) with at least one year of experience. The county contains a total of thirty-seven public high schools and a total of 4,857 teachers. All teachers selected in the sample will be asked to complete a short survey. Describe a sampling plan that would allow the researchers to obtain the desired information.

Accepted Answer

The answer of A study is to be undertaken to...

Exam 12: Experimental Design: Controlling Variation

Which statement is not true about randomized block designs?

Which of the following is not an important principle that should always be kept in mind when reading research articles containing statistical research results?

Suppose a sociologist is interested in finding out if there is an association between gender and opinions on human cloning. Which test design would be most appropriate for this scenario?

Which of the following is not a benefit of a stratified sampling plan?

Suppose a gumball manufacturer decides to inspect every twenty-fifth gumball for defects. What kind of sampling does this illustrate?

Which of the following is not a primary factor that affects the power of a test?

Which of the following statements is not true about a systematic sampling plan?