Is there a bias in this sampling method? Explain.

Question

A restaurant chain’s owners are trying to decide if they want to open up a franchise in your town. To help them decide, they want to find out how often people in your town go out to eat. A researcher interviews people leaving a local restaurant.

Answer 1

If the objective is to find out how often a typical person eats out, this is obviously biased because they are interviewing people who are leaving a restaurant. It means that the people in the sample are already inclined to eat out. What they should do is interview a random sample of people in the town and ask them how often they eat out.

Answer 2

Hi Erika! The problem you listed would actually fall under this concept of bias where the data is skewed because the sample is not a representative portion of the population. In this case, because the person who is the interviewer is talking to people who are eating at restaurants, this implies that the sample tends to eat out more frequently. For proper sampling, the interviewer could collect a list of all the people who live in the town and then randomly collect names to figure out the true data. Hope that helps!