Exam 6: Gathering Useful Data for Examining Relationships

Use the following information for questions: You wish to study the effect of a tutoring program to help improve student grades in an introductory statistics course. -Propose a matched-pairs study design to answer the question.

Use the following information for questions: Decide if the study is an observational study or an experiment. -A medicine to remove the redness in eyes was tested in a group of 100 students. Each student took the medicine in one eye and a placebo in the other eye. The eye (left or right) that received the placebo was decided by flipping a coin.

When subjects receive subtle cues from the researchers about what outcomes are expected, the effect is called

When the results of a study on adults is applied to children, the effect is called

In an observational study, confounding means

Use the following information for questions: A study of changing speed limits in the United States finds no evidence that higher limits fuel more deaths. A scientist examined shifts in speed limit laws over the past few decades. Highway speed limits were initially throttled in the 1970s in response to the gas shortage. In the 1980s the focus shifted to public safety. Yet in 1995, Congress returned all speed limit authority back to the states, and many states raised their top highway speeds. While limits ranged from 75 mph to 55 and back again, no significant increase in fatalities per mile driven are evident. In fact, from 1968 to 1991, the fatality rate per 100 million miles declined by 63.2 percent. The scientist attributes the decrease to safer cars, increased use of seat belts, an increase in the minimum legal drinking age, and better road maintenance. "Automobile safety features and enforcement emerge as important factors in increasing highway safety,"the scientist contends. "Speed limits are far less important." -In the study "safer cars, increased use of seat belts, an increase in the minimum legal drinking age, and better road maintenance" are mentioned as reasons for a decline in the fatality rate between 1968 and 1991. What do we call these 4 variables?

A study was conducted to compare the grade point averages (GPAs) of male and female students majoring in Psychology. In this study

Use the following information for questions: A researcher is studying the relationship between sugar consumption and weight gain. Twelve volunteers were randomly assigned to one of two groups. The first group had five participants which were put on a diet low in sugar and the other group with the remaining seven participants received 10% of their calories from sugar. After 8 weeks, weight gain was recorded from each participant. -Which variable is the response variable in this study?

Use the following information for questions: Research is done to see whether taking oral contraceptives increases women's blood pressures. The blood pressures of women who take oral contraceptives are compared to the blood pressures of women who do not take oral contraceptive. A complicating factor is that the women who take oral contraceptives tend to be younger than the others. This must be taken into account because blood pressure increases with age. -Which variable is a confounding variable in this study?

Use the following information for questions: Decide if the study is an observational study or an experiment. -A study compared the IQ from children whose mothers smoked to the IQ from children whose mothers didn't smoke.

Use the following information for questions: A researcher designed a study to assess whether grades in a statistics course could be improved by using a new teaching technique. The 250 students enrolled in a large introductory statistics class are also enrolled in one of 20 lab sections. The 20 lab sections are randomly divided into 2 groups of 10 lab sections each. The students in the first set of 10 lab sections are taught by this "new" method. The students in the remaining 10 lab sections are taught using the "old" techniques. The grades at the end of the term are then compared. Assume that the students do not know if the method they are being taught with is the old or the new method. -What type of study is described above? Explain your answer.

Use the following information for questions: For each relationship (conclusions from one or more studies), define what the response and explanatory variables are. -Listening to Mozart raised non-verbal IQ scores an average of 8 to 9 points higher than listening to relaxation tapes.

Use the following information for questions: Decide if the study is an observational study or an experiment. -One hundred adults who had either Type 1 or Type 2 diabetes were randomly divided into 2 groups to determine if the inhalable version of insulin is able to manage blood sugar levels just as well as injected insulin.

An experiment is usually preferred to an observational study because

Use the following information for questions: An observational study has found that drivers who report that they routinely wear a seatbelt were less likely to have been given a traffic ticket for speeding in the past three years. -Of the following, which is the most likely explanation for this observed relationship?

Use the following information for questions: You wish to study the effect of a tutoring program to help improve student grades in an introductory statistics course. -Propose an experimental study design to answer the question.

A large international trial recruited 7,000 healthy women and randomly assigned them to receive either tamoxifen or a placebo. The women were followed for a number of years and the breast cancer rates were compared between the two groups. Neither the women nor the treating physicians knew which treatment the women were actually receiving. Which of the following does not apply to this study?

Use the following information for questions: Fifty university students are randomly chosen from the college campus. Their physical fitness routines and academic performance will be assessed. They are asked to maintain a diary over a semester to record their physical activity (i.e. work-outs) every week. At the end of this semester their GPA is recorded as well. The resulting information is categorized per student into two variables: physical activity (recorded as "above average", "average", or "below average") and that semester's GPA. The primary interest of the research project is to understand if physical activity promotes better academic performance. -What type of study is this?

Use the following information for questions: Research is done to see whether taking oral contraceptives increases women's blood pressures. The blood pressures of women who take oral contraceptives are compared to the blood pressures of women who do not take oral contraceptive. A complicating factor is that the women who take oral contraceptives tend to be younger than the others. This must be taken into account because blood pressure increases with age. -Which variable is the response variable in this study?

Use the following information for questions: Researchers would like to compare meditation and exercise to see which is more effective for reducing stress. One hundred people who suffer from high stress volunteer to participate in a study for ten weeks. Participants will either be given a 10-week course in meditation or will participate in a 10-week exercise program. The researchers must decide whether to randomly assign the volunteers to the two programs, or allow them to choose. -Which of the following is an advantage of allowing participants to choose the program in which to participate?