Aprofessional society, with a membership of 45,000, is designing a study to evaluate their membership's satisfaction with the type of sessions presented at the society's annual meeting. In each of the following descriptions of the method of selecting participants in the survey, identify the type of sampling method used (simple random sampling, stratified sampling, or cluster sampling).
a. The society has an alphabetical listing of all its members. They assign a number to each name and then using a computer software program they generate 1,250 numbers between 1 and 45,000. They select these 1,250 members for the survey.
b. The society is interested in regional differences in its membership's opinion. Therefore, they divide the United States into nine regions with approximately 5,000 members per region. They then randomly select 450 members from each region for inclusion in the
survey.
c. The society is composed of doctors, nurses, and therapists, all working in hospitals. There are a total of 450 distinct hospitals. The society decides to conduct onsite in-person interviews, so they randomly select 20 hospitals and interview all members working at the selected hospital.