PROBLEMS – SAMPLING METHODS

In the following exercises, identify which of these types of sampling is used: random, systematic, convenience, stratified, or cluster.

1. A medical student researches the prevalence of aspirin usage by questioning all the patients who enter her clinic for treatment.

2. The Connecticut Department of Health obtains an alphabetical list of 2,537,243 adult Connecticut residents and constructs a pool of survey subjects by selecting every 1000th name on the list.

3. In A Gallup poll of 1059 adults, the interview subjects were selected by using a computer to randomly generate telephone numbers that were then called.

4. A dietitian has partitioned people into age categories of under 18, 18-49, 50-69, and over 69. She is surveying 200 members from each category.

5.. Motivated by a student from binge drinking, the College of Newport conducts a study of student drinking by randomly selecting 10 different classes and interviewing all of the students in each of those classes.

6. In phase II testing of a new drug designed to increase the red blood cell count, a researcher creates envelopes with the names and addresses of all treated subjects. She wants to increase the dosage in a subsample of 12 subjects, so she thoroughly mixes all of the envelopes in a bin, then pulls 12 of those envelopes to identify the subjects to be given the increased dosage.

7. One of the authors observed a sobriety checkpoint at which every 5th driver was stopped and interviewed.

8. A farmer has 5267 orange trees. She randomly selects 20 trees, then picks all of the oranges on those trees and measures the sugar content in each orange.

9. A researcher is studying the effect of education on health and conducts a survey of 150 randomly selected workers from each of these categories: less than a high school diploma; high school degree; more than a high school degree.

10. A statistics student obtains height/weight data by interviewing family members.

11. A John Hopkins Hospital University researcher surveys all cardiac patients in each of 30 randomly selected hospitals.

12. In studying the incidence of AIDS, an epidemiologist is planning a survey in which 500 people will be randomly selected from each of these groups: unmarried adult men, married adult men, unmarried adult women, married adult women.