Exam 12: Experimental Design: Controlling Variation

Use the following information to answer the question. These two headlines are on the same topic. Headline A: Married men who gain weight following the birth of their first child dramatically increase their risk of further weight gain following the birth of more children, a new study suggests. Headline B: Married male weight gain after the birth of the first child leads to additional weight gain following the birth of more children, a new study finds. -Was the study referenced most likely a controlled experiment or an observational study?

Purple Loosetrife is considered an invasive plant in Michigan. To detect the presence of Purple Loosetrife on public land, environmental researcher's partition land into one acre parcels then randomly select a sample of parcels to be fully inspected for the presence of Purple Loostrife. What kind of sampling does this illustrate?

Suppose state lawmakers are interested in finding out whether a newly instituted state program about distracted driving is effective. A statistician divides the state into three regions then randomly selects a sample of adult licensed drivers from each region. Participants are then asked to fill out a questionnaire about distracted driving. What kind of sampling does this illustrate?

An office building janitorial company is interested in the opinions of people who visit the office building on a typical day. He thinks that opinions of people who visit the office building in the morning could be different than those who visit later in the day and he does not want a biased sample. Which sampling method is likely to result in an unbiased sample?

Suppose a large donation has been left to a local community college by a private donor. School officials have decided that one option for the money would be to build a new gymnasium for student and community use. It is decided that a stratified sampling plan would be the best way to get input from the public about this option since opinions within a stratum are likely to be similar. What would be a reasonable way to stratify the population?

Use the following information to answer the question. A researcher wonders whether speed of service at a diner is affected by whether a male customer is wearing a suit jacket. The researcher used the following study design to collect data: The researcher chose five diners in a large city and recorded the number of male customers that wore a suit jacket during a two week period. He also records how long it took a waiter or waitress to address the customer. He finds that male customers who wear suit jackets were addressed by the wait staff faster than male customers who did not wear a suit jacket. -Choose the statement that correctly explains why we can or cannot make a cause- and- effect conclusion.

Suppose a sleep expert conducts a study to detect the effects of a new doctor- recommended breathing and relaxation routine on insomnia. Hours of sleep per night were measured for participants before starting the routine and four weeks after using the breathing and relaxation routine just before bed. Which test design would be most appropriate for this scenario? Explain.

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?

Suppose it was reported on the news that a recent study concluded that the probability that you will get brain cancer if you use a cell phone more than doubled from 1 in 460,000 to 1 in 230,000. Choose the statement that best summarizes the significance of this result.

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

Suppose a large endowment has been left to your city by a private donor. The city council has decided that the endowment should be used to build an activity center near the center of town. One option is to build an activity center for senior citizens. It is decided that a stratified sampling plan would be the best way to get input from the public since opinions within a strata are likely to be similar. Which method for stratifying seems to be most reasonable for this scenario?

Use the following information to answer the question. These two headlines are on the same topic. Headline A: Gaining weight after giving birth for the first time leads to pregnancy- related diabetes during second pregnancy, a new study finds. Headline B: Women who gain weight after giving birth for the first time dramatically increase their risk of developing pregnancy- related diabetes during their second pregnancy, a new study suggests. -Was the study referenced most likely a controlled experiment or an observational study?

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

Use the following information to answer the question. 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?

Suppose a large endowment has been left to your city by a private donor. The city council has decided that the endowment should be used to build a recreation park near the center of town. One option is to build a skate park. It is decided that a stratified sampling plan would be the best way to get input from the public since opinions within a strata are likely to be similar. Which method for stratifying seems to be most reasonable for this scenario?

Which workout recovery drink is better: water, a fortified sports drink, or chocolate milk? In a study, researchers randomly assigned 50 similar athletes to one of three groups. All subjects participated in the same workout. Depending on which group they were assigned to, subjects then drank 12 ounces of water, a fortified sports drink, or chocolate milk. Afterwards, subjects were measured for muscle fatigue. Researchers found that the athletes that drank chocolate milk after a workout recovered from muscle fatigue faster than either those who drank water or the sports drink. For this controlled experiment, identify the treatment and the response variables.

The Sirex Noctilio, a wood wasp, is considered an invasive species in Michigan and can harm and even kill pine trees. To detect the presence of the wood wasp on public land, environmental researchers partition land into one acre parcels then randomly select a sample of parcels to be fully inspected for the presence of the wood wasps in pine trees. What kind of sampling does this illustrate?

Use the following information to answer the question. 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.

Use the following information to answer the question. 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.

Use the following information to answer the question. These two headlines are on the same topic. Headline A: Gaining weight after giving birth for the first time leads to pregnancy- related diabetes during second pregnancy, a new study finds. Headline B: Women who gain weight after giving birth for the first time dramatically increase their risk of developing pregnancy- related diabetes during their second pregnancy, a new study suggests. -Which one has language that suggests a cause- and- effect relationship?