The term "demographics" is a colloquialism that derives from demography, "the study of the characteristics of human populations." Professional demographers, such as those who work at the United States Census Bureau, are concerned primarily with population size and density, birth and death rates, and in- and out-migration. But the practice of describing human groups according to distributions of sex, age, ethnicity, educational level, income, or other such has become a commonplace in many domains. These categories are called demographics.

In the television industry demographics are used in various ways, most of which can be characterized as either descriptive or analytical. First, demographics can be used to describe an audience. Such descriptive uses may be applied to an actual audience, as, for example: 54% female, 62% white, average age 44. Or demographics may be used to describe a desired audience, as in "younger," or "higher income."

Second, demographics can be used to sort data about people for purposes of analysis. For example, data may be available from a study designed to assess people's evaluations of an evening newscast anchor. Researchers may be interested in the average evaluation across people, in the evaluations of specific subgroups of people, or in the differences between the evaluations of specific subgroups. For either of the latter two purposes one would divide the data according to the demographic categories of interest and calculate averages within those categories. It would then be possible to report the evaluations of women as distinct from those for men, those for higher and lower education groups, and so on.

Advertisers' interest in demographics arises from market research or advertising strategies that emphasize certain types of people as the target audience for their advertising. Commercial broadcasters, then, who earn their living by providing communication services to advertisers, are interested in demographics because the advertisers are. Because advertisers are more interested in some demographic categories than others, the commercial broadcasters have a financial interest in designing programming that appeals to people in those more desired demographic categories.

Independent of the specific advertising connection, demographic categories are also be used whenever generalizations are more important than precision. Individuals are sometimes interested in saying something more generally than precisely true. But for national television programmers, who must think in terms of audiences of several million people at a time, there is no other option. So their work is characterized by reliance on such generalizations as women like romance, men like action, young people won't watch unless we titillate them.

Uses of demographics to define and generalize about people is an instance of social category thinking. The rationale is that the available social categories, such as age, gender, ethnicity, and educational level, are associated with typical structures of opportunity and experience that in turn produce typical patterns of disposition, attitudes, interests, behaviors, and so on. The application of social category thinking often extends beyond that sensible rationale to include any instance where differences in a variable of interest can be associated with conveniently measured demographic differences. Age, for example, is easy to measure, amenable to being categorized, and associated with a great variety of differences in taste and activity. No one, of course, supposes that aging causes people to watch more television; but older adults do watch more than younger adults. The convenience of that knowledge outweighs the need for precision in the television industry.

-Eric Rothenbuhler