Public opinion is the aggregate of inividual attitudes or beliefs held by the adult population. The principle approaches to the study of public opinion may be divided into 4 categories: a) quantitative measurement of opinion distributions b) investigation of the internal relationships among the individual opinions that make up public opinion on an issue c) description or analysis of the public role of public opinion. d) study both of the communication media that disseminate the ideas on which opinions are based and of the uses that propagandists and other manipulators make of these media.