A survey can measure almost any characteristic in a population, such as health condition, physical characteristics, and income. Surveyors concerned with assessing the proportion of people in a population who hold an attitude or opinion want an absolute measure of a population. The objective of a survey usually is not to assess causality, but to measure the attitudes or opinions of a population at a point in time. In most surveys, the measuring instrument is the questionnaire. Whether administered orally or in written form, the building blocks of the questionnaire are queries or questions demanding a response. The chapter explores the relationships among people’s attitudes and to compare attitudes of people in different segments of the population. Questions about psychological states ask about a person’s attitudes or opinions. The answers to such questions are not easily verified unless the attitudes or opinions are clearly linked to specific actions.