Question

12 points) While obesity is measured based on body fat percentage (more than 35% body fat for women and more than 25% for men), precisely measuring body fat percentage is difficult. Body mass index (BMI), calculated as the ratio weightheight2weightheight2 is often used as an alternative indicator for obesity. A common criticism of BMI is that it assumes the same relative body fat percentage regardless of age, sex, or ethnicity. In order to determine how useful BMI is for predicting body fat percentage across age, sex and ethnic groups, researchers studied 202 black and 504 white adults who resided in or near New York City, were ages 20-94 years old, had BMIs of 18-35 kgm2kgm2, and who volunteered to be a part of the study. Participants reported their age, sex, and ethnicity and were measured for weight and height. Body fat percentage was measured by submerging the participants in water.

1. The paragraph above describes a
A. Experiment
B. Observational Study

2. What are the cases?
A. 706 adults residing in or near New York City
B. Age, sex, and ethnicity
C. The calculated body mass index (BMI)
D. People between age 20 and 94

3. Match the variable to its type:
Ethnicity:  ? Categorical Numerical  
Sex:  ? Categorical Numerical  
Age:  ? Categorical Numerical  
BMI:  ? Categorical Numerical  
Body fat percentage:  ? Categorical Numerical

4. What is the research question?
A. What is the average body fat percentage for New York City residents?
B. Is body mass index a good indicator for obesity?
C. How should researchers measure body fat percentage?
D. Do study volunteers have less obesity than average New York City residents?

5. What is the population of interest?
A. Residents of New York City who are obese
B. All methods to measure obesity
C. All ethnic groups
D. All adults

6. What is the sample?
A. New York City residents
B. The calculated BMI of the study participants
C. 20-94 year olds
D. The 202 black and 504 white men and women who participated in the study

7. Can the findings of the study be generalized to the population?
A. No, because the participants volunteered to be a part of the study.
B. Yes, because there was racial diversity among the subjects.
C. No, because the measurements might be inaccurate.
D. Both a and c

8. Can the findings of this study be used to establish causal relationships?
A. Yes, because the subjects volunteered to participate
B. No, because this is an observational study
C. Yes, because this was an experiment
D. No, because this is an experiment

Answer 1

Answer: