Hi
A poll of 20,000 randomly selected college students in the US determined that during the current semester 45% purchase all their course texts from the campus bookstore.
Population: All college students in the US
Sample: The 20,000 randomly selected college students
Variable: Venue used by students for purchasing course texts (For ex: College Bookstore)
Type of Study: observational | NOte: In an observational study investigators
observe subjects and measure variables of interest without assigning treatments to the subjects.