Predictions of Public Opinion from the Mass Media. Computer Content Analysis and Mathematical Modeling

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THEORY AND METHODOLOGY FAN, DAVID P., Predictions of Public Opinion from the Mass Media. Computer Content Analysis and Mathematical Modeling. New York: Greenwood Press, 1988. 220 pp. $42.95.

The author has developed an ambitious computer technique for content analysis and mathematical modeling in order to predict the development of public opinion from media content.

A member of the Department of Genetics and Cell Biology at the University of Minnesota, he calls his approach ideodynamics, a mathematical model in which message components are assigned "persuasive force functions." He calls such a message component an "infon," defined as a "message component favoring one of the possible positions being considered." He uses an elaborate computer content analysis of Associated Press stones to determine the persuasive potential of media information, and from this, predicts changes in public opinion, operationalized as fluctuations in public opinion polls.

The polls come from the Roper Center at the University of Connecticut. The issues involve defense spending, aid to the Contras, the presence of American troops in Lebanon and the 1984 presidential election.

He summarizes his approach as follows: "The general rule in ideodynamic calculations is that all opinion conversions increase with the sizes of the target subpopulations and the magnitudes of the persuasive force functions, which depend in turn on the infons' contents, validities and audience sizes." Any message can be made up of a number of infons, including the position it favors, whether it is direct or indirect in its support, and thirdly, the nature of the source of the message. The validity of a message refers to the reputation of the medium through which it comes.

Much of the book and appendices is spent in descriptions of the various formulas used to conduct the ideodynamic calculations and make the predictions. Another large portion of the book is spent in discussing the computer content analysis technique. The book's major contributions are these analytical innovations. Both seem to have a number of applications, both in this area and in others.

The book's great weakness is in the author's assumptions about the public opinion formation process. …