Exam 5: Causation: Can We Say What Caused the Effect

January 22, 2016, NPR news headline reads "Why Poverty May Be More Relevant Than Race For Childhood Obesity." The article states, "At first glance it looked like childhood obesity was more common among African Americans or Hispanics... When they accounted for poverty, though, the trend vanished." The study collected data on a random sample of K-12 students in Massachusetts. In this study, whether or not a child lives in poverty is an example of a

A study published in 2007 by Christopher Johnson, professor of music education and music therapy at the University of Kansas, revealed that students in elementary schools who took private music lessons scored around 20 percent higher in math scores on standardized tests, compared to students who did not take private music lessons. -What is the response variable?

A study was done to compare the lung capacity of coal miners to the lung capacity of farm workers. The researcher studied 200 workers of each type. Other factors that might affect lung capacity are smoking habits and exercise habits. The smoking habits of the two worker types are similar, but the coal miners generally exercise less than the farm workers -Which of the following is the explanatory variable in this study?

A randomized experiment was done by randomly assigning each participant either to walk for half an hour three times a week or to sit quietly reading a book for half an hour three times a week. At the end of a year the change in participants' blood pressure over the year was measured, and the change was compared for the two groups. -This is a randomized experiment rather than an observational study because:

Babies born with low birth weights (less than 2500 grams) are at an increased risk for many infant diseases. Researchers in North Carolina collected data to see what variables may influence the birth weight (in grams) of a child, including whether the mother drank alcohol during pregnancy, whether the mother smoked during pregnancy, the mother's age (years), the gestation of the pregnancy (number of weeks from conception until birth), the mother's race, the length of the birth (hours), and several others. The following plot was created to summarize some of the data collected. -What is the response variable in this study?

A study was done to compare the lung capacity of coal miners to the lung capacity of farm workers. The researcher studied 200 workers of each type. Other factors that might affect lung capacity are smoking habits and exercise habits. The smoking habits of the two worker types are similar, but the coal miners generally exercise less than the farm workers -Which of the following is a confounding variable in this study?

A randomized experiment was done by randomly assigning each participant either to walk for half an hour three times a week or to sit quietly reading a book for half an hour three times a week. At the end of a year the change in participants' blood pressure over the year was measured, and the change was compared for the two groups. -If a statistically significant difference in blood pressure change at the end of a year for the two activities was found, then:

The following table shows the responses from a sample of 680 people in the General Social Survey to the question, "Do you sometimes drink more than you think you should?" -Does there appear to be an association between gender and whether a person responds that they drink more than they should?

A study published in 2007 by Christopher Johnson, professor of music education and music therapy at the University of Kansas, revealed that students in elementary schools who took private music lessons scored around 20 percent higher in math scores on standardized tests, compared to students who did not take private music lessons. Is this a randomized experiment or an observational study?

According to the 2020 Bureau of Transportation Statistics , 55.7% of flights arrive on-time. Of those flying Delta, 67.6% of flights arrive on time. However, only 47.0% of flights arrive on time for those flying Southwest. -Does there appear to be an association between the airline company (Delta or Southwest) and if a flight arrives on time?

The following table shows the responses from a sample of 680 people in the General Social Survey to the question, "Do you sometimes drink more than you think you should?" -What proportion of those that responded they drink more than they should are female?

Babies born with low birth weights (less than 2500 grams) are at an increased risk for many infant diseases. Researchers in North Carolina collected data to see what variables may influence the birth weight (in grams) of a child, including whether the mother drank alcohol during pregnancy, whether the mother smoked during pregnancy, the mother's age (years), the gestation of the pregnancy (number of weeks from conception until birth), the mother's race, the length of the birth (hours), and several others. Is this a randomized experiment or an observational study?

In a study on sleep habits, it was found that college students who got at least 7 hours of sleep the night before a test performed better on exams than college students who got less than 7 hours of sleep. -Identify the explanatory and response variables in this study.

According to the 2020 Bureau of Transportation Statistics , 55.7% of flights arrive on-time. Of those flying Delta, 67.6% of flights arrive on time. However, only 47.0% of flights arrive on time for those flying Southwest. -Which of the following values are conditional probabilities in this scenario? Select all that apply.

In a study on sleep habits, it was found that college students who got at least 7 hours of sleep the night before a test performed better on exams than college students who got less than 7 hours of sleep. -In the following diagram, fill in the blanks to describe a potential confounding variable in this study. Drop-down menu for (1) and (2): •Enrolled in more credit hours •Enrolled in less credit hours •Perform better on exams •Perform worse on exams

In a study on treatments for anorexia, researchers recruited 30 teenage girls with anorexia. The girls were ranked by weight prior to the study. Of the heaviest three girls, one was randomly assigned to a "family" therapy, one to a "cognitive/behavioral" therapy, and one to a control group. The same was done for the next three heaviest girls, down to the three lightest girls. After five weeks of treatment, researchers weighed the participants. Researchers would like to determine which, if any, of the treatments are most effective in treating anorexia. -If the researchers found that there were statistically significant differences in average weight across the three treatments, would they be justified in concluding that the treatments caused the changes in weights?

A study published in 2007 by Christopher Johnson, professor of music education and music therapy at the University of Kansas, revealed that students in elementary schools who took private music lessons scored around 20 percent higher in math scores on standardized tests, compared to students who did not take private music lessons. -Which of the following could be a potential confounding variable?

In a study on treatments for anorexia, researchers recruited 30 teenage girls with anorexia. The girls were ranked by weight prior to the study. Of the heaviest three girls, one was randomly assigned to a "family" therapy, one to a "cognitive/behavioral" therapy, and one to a control group. The same was done for the next three heaviest girls, down to the three lightest girls. After five weeks of treatment, researchers weighed the participants. Researchers would like to determine which, if any, of the treatments are most effective in treating anorexia. -What type of study design did the researchers use?

Sickle-cell disease is a painful disorder of the red blood cells. To investigate whether drug A can reduce the pain associated with sickle-cell disease, a study by the National Institutes of Health randomly assigned 150 sickle-cell sufferers to receive the drug. Placebos were given to another 150 sickle-cell sufferers. Great care was used to ensure that the 300 participants did not know if their pill contained the drug. At the end of the treatment period, the researchers counted the number of episodes of pain reported by each subject. -Which of the following principles was NOT used in this study?

Sickle-cell disease is a painful disorder of the red blood cells. To investigate whether drug A can reduce the pain associated with sickle-cell disease, a study by the National Institutes of Health randomly assigned 150 sickle-cell sufferers to receive the drug. Placebos were given to another 150 sickle-cell sufferers. Great care was used to ensure that the 300 participants did not know if their pill contained the drug. At the end of the treatment period, the researchers counted the number of episodes of pain reported by each subject. -What type of study is this?