A 2002 Gallup survey interviewed by phone a random sample of 474,195 U.S. adults. Participants were asked to describe their work status and to report their height and weight (to determine obesity based on a body mass index greater than 30). Gallup found 24.9% obese individuals among those interviewed who were employed (full-time or part-time by choice), compared with 28.6% obese individuals among those interviewed who were unemployed and looking for work.
What is the best description of the sample in this study?

Question

Quizplus · Accepted Answer

The sample is a random sample because respondents were chosen at random from a larger population. There is no indication that the sample was stratified or that respondents self-selected to participate, making options B and C incorrect. The sample does not represent a specific cohort (a group with a shared characteristic), such as people born in a particular year, so option D is also incorrect.

A 2002 Gallup Survey Interviewed by Phone a Random Sample