Question 1

Use the following information for following questions:. Which treatment is most effective at
treating bathroom mildew: water mixed with vinegar, ammonia, or soap? In a study, researchers randomly
assigned 55 similar tile samples with similar amounts of mildew to one of three groups. Depending on
which group they were assigned to, each tile sample received a home remedy of water mixed with
vinegar, ammonia, or soap. Afterwards, each tile sample was examined and any remaining mildew was
measured. Researchers found that a soap and water mixture produced better results than both vinegar and
ammonia.
-Write a statement that restates the conclusion of the study in terms of a cause-and-effect conclusion.

Accepted Answer

A soap and water mixture effectively treats mildew stains on tile compared to vinegar and ammonia.

Question 2

Use the following information for following questions:. A researcher wonders whether length of
time that it takes to hail a taxi is affected by the gender of the person hailing the taxi. The researcher used
the following study design to collect data: The researcher chose five busy intersections in a large city and
recorded the number of males and females who hailed a taxi. He also records how long it took to get a
taxi to stop. He finds that male customers waited a shorter period of time than females waited for a taxi.
-Restate the conclusion of the study in terms of a cause-and-effect conclusion. Explain why we can or cannot make a cause-and-effect conclusion.

Accepted Answer

Possible cause-and-effect conclusion: Being male leads to shorter wait times for a taxi, a new study finds. This was an observational study. Since random assignment was not used, we cannot conclude that being male caused the taxis to stop faster.

Question 3

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

Answers will vary, but cluster sampling is likely to be a reasonable choice. One could randomly select high schools from the thirty-seven and then survey all teachers in the selected high schools.

Question 4

Does listening to music improve efficiency for mundane tasks? In a study, researchers randomly assigned 50 similar adults to one of three groups. All subjects were asked to stuff 400 envelopes. Depending on which group they were assigned to, subjects heard Top 40 music, classical music, or no music while they worked. Researchers recorded how long it took the participants to stuff the envelopes. Researchers found that the adults that listened to no music completed the work faster than both the group that listened to Top 40 music and classical music. For this controlled experiment, state the treatment and the response variables.

Accepted Answer

The answer of Does listening to music improve efficiency for...

Question 5

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 6

Use the following information for following questions:. A researcher wonders whether length of
time that it takes to hail a taxi is affected by the gender of the person hailing the taxi. The researcher used
the following study design to collect data: The researcher chose five busy intersections in a large city and
recorded the number of males and females who hailed a taxi. He also records how long it took to get a
taxi to stop. He finds that male customers waited a shorter period of time than females waited for a taxi.
-Explain why we can or cannot generalize these results to a larger population.

Accepted Answer

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

Question 7

Write at least two questions that you should ask yourself when reading articles containing statistical research results. Explain why these questions are important.

Accepted Answer

The answer of Write at least two questions that you...

Question 8

selected office for each of the twelve months prior to the exercise program and then for each of the
twelve months after the exercise program is initiated. The "before" and "after" expenses are
compared on a month-to-month basis. Which test design would be the most appropriate for this
scenario?
-Recently, it was reported that the proportion of people using seatbelts while driving has begun to drop after years of steady increases. To determine the proportion of drivers using seatbelts in a particular community, it was decided to set up a checkpoint on a busy road and stop every twentieth driver to see if he/she was using a seatbelt. What kind of sampling does this illustrate?

Accepted Answer

The answer of selected office for each of the twelve...

Question 9

selected office for each of the twelve months prior to the exercise program and then for each of the
twelve months after the exercise program is initiated. The "before" and "after" expenses are
compared on a month-to-month basis. Which test design would be the most appropriate for this
scenario?
-A corporation desires to estimate the total number of worker-hours lost for a given month because of accidents among all employees. Because laborers, technicians, and administrators have different accident rates, the researcher decides to randomly select employees from each of the three groups and records the number of worker-hours lost for the given month for each employee. What kind of sampling does this illustrate?

Accepted Answer

The answer of selected office for each of the twelve...

Question 10

selected office for each of the twelve months prior to the exercise program and then for each of the
twelve months after the exercise program is initiated. The "before" and "after" expenses are
compared on a month-to-month basis. Which test design would be the most appropriate for this
scenario?
-A researcher is interested in knowing how satisfied people who live in independent living facilities are with their living conditions. To answer this question, the researcher randomly selects 50 independent living facilities from throughout the United States and asks each resident of the selected facilities how satisfied he/she is with his/her current living conditions. What kind of sampling does this illustrate?

Accepted Answer

The answer of selected office for each of the twelve...

Question 11

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 12

selected office for each of the twelve months prior to the exercise program and then for each of the
twelve months after the exercise program is initiated. The "before" and "after" expenses are
compared on a month-to-month basis. Which test design would be the most appropriate for this
scenario?
-Describe one benefit to a stratified sampling plan.

Accepted Answer

The answer of selected office for each of the twelve...

Question 13

Suppose it was reported on the news that a recent study concluded that pollutants in the air have dramatically increased our chances of getting a rare form of skin cancer from 1 in 250,000 to 1 in 150,000. Compare the clinical and statistical significance of this result.

Accepted Answer

The answer of Suppose it was reported on the news...

Question 14

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 15

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 16

List three factors that affect the statistical power of a test. Be sure to list the factor over which researchers actually have some control.

Accepted Answer

The answer of List three factors that affect the statistical...

Question 17

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

Accepted Answer

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

Question 18

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. What would be a reasonable way to stratify the population?

Accepted Answer

The answer of The city council of a moderate size...

Question 19

selected office for each of the twelve months prior to the exercise program and then for each of the
twelve months after the exercise program is initiated. The "before" and "after" expenses are
compared on a month-to-month basis. Which test design would be the most appropriate for this
scenario?
-Describe a situation where a systematic sampling plan would be appropriate.

Accepted Answer

The answer of selected office for each of the twelve...

Question 20

selected office for each of the twelve months prior to the exercise program and then for each of the
twelve months after the exercise program is initiated. The "before" and "after" expenses are
compared on a month-to-month basis. Which test design would be the most appropriate for this
scenario?
-Describe one benefit to a cluster sampling plan.

Accepted Answer

The answer of selected office for each of the twelve...

Quiz 12: Experimental Design: Controlling Variation

Write at least two questions that you should ask yourself when reading articles containing statistical research results. Explain why these questions are important.

Suppose it was reported on the news that a recent study concluded that pollutants in the air have dramatically increased our chances of getting a rare form of skin cancer from 1 in 250,000 to 1 in 150,000. Compare the clinical and statistical significance of this result.

List three factors that affect the statistical power of a test. Be sure to list the factor over which researchers actually have some control.