Is the survey based on a representative sample?
A sample is considered to be representative of a population if the relevant characteristics of the population are reflected in the sample. So, considering the population of interest is critical in evaluating the quality of a sample. Our survey sample is drawn from the population of subscribers to ConsumerReports.org and to Consumer Reports magazine. While all subscribers are invited to participate in the survey, participation is voluntary, and there is always the possibility that those who respond are unique in some particular way. For example, subscribers have sometimes questioned whether those who respond are those who have a complaint to make about their cars. To address this concern, we conduct a validation test every year. A representative sample of 8,000 to 10,000 subscribers are mailed the same questions about problem experiences with their cars at the same time as all subscribers are asked to complete the main survey. Using a combination of incentives and follow-up mailings, we
