Sherman wants to know which toothpaste dentists in his state recommend, so he calls 20 dentists in his county.
Correct! Not every dentist in Sherman’s state had an equal chance of being selected for the survey. This sample is non-random and is called a convenience sample.
Incorrect. For the sample to be random, every dentist in the state has to have an equal chance of being selected for the sample. Sherman only called dentists in his county, not in counties across the state.
Kylie wants to know which foods the 8th graders in her school like best. She waits at the entrance door of the cafeteria during 8th grade lunch and surveys every 5th student entering the cafeteria.
Correct! Every 8th grade student has an equal chance of being selected for the sample. This sample is random and is called an interval sample.
Incorrect. Since the students are not assigned an entry sequence into the cafeteria, each student has an equal chance of being selected for the sample.
Mervin wants to know how students in his middle school feel about the starting time for 1st period. He uses a random number generator to select 75 student identification numbers and surveys those students.
Correct! Every student has an equal chance of being selected for the sample.
Incorrect. Mervin is using a random number generator to select students from a list, so each student has an equal chance of being selected for the sample.
Jacqueline wants to know how students in her school feel about the choices for a new school mascot, so she surveys her classmates.
Correct! Not every student in Jacqueline’s school had an equal chance of being selected for the survey. This sample is non-random and is called a convenience sample.
Incorrect. Every student in the school may not be one of Jacqueline’s classmates, so they do not have an equal chance of being selected for the sample.
Nneka hosts an Internet talk show and wants to know how people in her town feel about the recent football season. She invites viewers to type their responses in a chat room.
Correct! Not every person in Nneka's town had an equal chance of being selected for the survey. This sample is non-random and is called a voluntary-response sample.
Incorrect. Every person in Nneka's town may not be a viewer of her Internet talk show, and will not have an equal chance of being selected for the sample.