Exam 17: Turning Information Into Wisdom

Use the following information for questions: In a report by AP, the headline read "Even light weekend use of the party drug Ecstasy might harm intelligence, a study suggests". The headline was based on a study of 28 Ecstasy users in their mid-20s recruited off the dance floor of a nightclub. The researchers compared this group with two others of the same size, age range, and education level - one consisting of drug-free people and another of people who smoked about as much marijuana as the Ecstasy group. The researchers reported weeks after partying, those who used Ecstasy along with marijuana performed worse on intelligence tests than people who just smoked marijuana or took no drugs at all. -What was the response variable?

A random sample of 5000 students were asked whether they prefer a 10 week quarter system or a 15 week semester system. Of the 5000 students asked, 500 students responded. The results of this survey ________

In a study for which the sample represents the population of interest but the treatments are not randomly assigned

Use the following information for questions: Twenty volunteers were assigned at random to one of two groups (10 people in each group). One group would take Vitamin C for two weeks, while the second group would take a placebo. At the end of the study, the proportion of colds in the two groups will be compared. -What is the response variable in the study?

A newspaper reported that researchers were surprised when a new study found no relationship between a certain food and a certain disease, because two previous studies had found a relationship. Which of the following is not likely to explain what happened?

Use the following information for questions: A random sample of 500 students showed a statistically significant relationship between where the students usually sat in class (front, middle, or back) and grade point average (GPA). -Can a conclusion that where a student sits in the classroom causes a change in GPA?

Use the following information for questions: A random sample of 100 students living in dormitories was selected to see whether students in dormitories were satisfied with the food being served in the cafeteria. -An additional group of 10 students, not selected in the sample, asked to be included so that their opinions could be heard. Adding these students to the sample

Use the following information for questions: An observational study found a statistically significant relationship between regular consumption of tomato products (yes, no) and development of prostate cancer (yes, no), with lower risk for those consuming tomato products. -Which of the following is not a possible explanation for this finding?

Use the following information for questions: A study of 42 patients with carpal tunnel syndrome (symptoms of burning numbness in the wrist to difficulty making a fist) was done ("Yoga based intervention for carpal tunnel syndrome," Garfinkel et al, JAMA 1998; 280:1601-1603). Subjects were randomly assigned to a yoga group or a control (where they were offered a wrist splint to supplement their current treatment). Results showed that subjects in the yoga group had significant improvement in grip strength, while subjects in the control group did not. -What is the explanatory variable in the study?

Use the following information for questions: In a report by ABC News, the headlines read "City Living Increases Men's Death Risk" The headlines were based on a study of 3,617 adults who lived in the United States and were more than 25 years old. One researcher said, "Elevated levels of tumor deaths suggest the influence of physical, chemical and biological exposures in urban areas… Living in cities also involves potentially stressful levels of noise, sensory stimulation and overload, interpersonal relations and conflict, and vigilance against hazards ranging from crime to accidents." -Is a conclusion that living in an urban environment causes an increased risk of death justified?

Use the following information for questions: A random sample of 100 students living in dormitories was selected to see whether students in dormitories were satisfied with the food being served in the cafeteria. -The conservative margin of error for the sample of 100 students is

Use the following information for questions: 43 sedentary adults between the ages of 50 and 76 were randomly assigned to either an exercise program four times a week for 16 weeks or they continued to be sedentary (King, et al, JAMA, January 1, 1997,pp 32-37). The exercise group slept an average of 42 minutes a night longer than the control group. -What is the explanatory variable in the study?

A Gallup Poll in 1997 asked "What do you think is the ideal number of children for a family to have?" In a random sample of 1000 Americans, aged 18 or older, 50% responded that having 0 to 2 children was ideal. What is the conservative margin of error for this sample?

Which of the following would not allow conclusions to be made about a population?

Use the following information for questions: In a report by Reuters, the headline read "Emotional Support Helps Breast Cancer Survival" The headline was based on a study of 847 women (442 black women and 405 white women) with breast cancer and how they fared over a 9-year period. The authors wrote "Women in our study who reported low levels of both emotional expression and emotional support experienced 2 to 4 times greater breast cancer mortality than women reporting high levels of both". -What type of study was this?

Explain why a cause and effect relationship can be inferred from a randomized experiment, but not from an observational study.

Use the following information for questions: In a study of 900 European American children born in 1991 ("Maternal Employment and Child Cognitive Outcomes in the First Three Years of Life: The NICHD Study of Early Child Care," Brooks-Gunn, Han, and Waldfogel, Child Development 73[2002]: 1052-1072), the authors wrote "children whose mothers worked at all by the ninth month of their life had lower [cognitive outcome] scores at 36 months than did children whose mothers did not work by that time." These results were statistically significant. -What is the response variable in this study?

Use the following information for questions: An observational study found a statistically significant relationship between regular consumption of tomato products (yes, no) and development of prostate cancer (yes, no), with lower risk for those consuming tomato products. -Which of the following is a valid conclusion from this finding?

Use the following information for questions: In a report by AP, the headline read "Even light weekend use of the party drug Ecstasy might harm intelligence, a study suggests". The headline was based on a study of 28 Ecstasy users in their mid-20s recruited off the dance floor of a nightclub. The researchers compared this group with two others of the same size, age range, and education level - one consisting of drug-free people and another of people who smoked about as much marijuana as the Ecstasy group. The researchers reported weeks after partying, those who used Ecstasy along with marijuana performed worse on intelligence tests than people who just smoked marijuana or took no drugs at all. -What type of study was this?

A large company examines the annual salaries for all of the men and women performing a certain job and finds that the means and standard deviations are $32,120 and $3,240, respectively, for the men and $34,093 and $3521, respectively, for the women. The best way to determine if there is a difference in mean salaries for the population of men and women performing this job in this company is