Learn in the textbookPopulation and Sampling
DefinitionGathering opinions or facts by having people answer a form that lists questions is called a questionnaire survey (アンケート調査).
ExplanationWhen there are many people to ask, it is usually run as a sample survey, sending the form to a part chosen from the population. How respondents are chosen, and who actually replies, can pull the results away from the true population. For example, if people who care strongly about the topic are more likely to reply, the collected opinions lean toward their side.
AnalogyIt is like finding out what students think of a new cafeteria dish by asking a few people who happen to be eating there at lunch.
Memory hookThe Japanese word アンケート comes from the French enquête, meaning "inquiry."