As audience measurement became more sophisticated, the television programmers followed. Television shows were developed not just for their entertainment value but to attract specific segments of the audience. There were programs aimed at teenagers, special shows for women, others targeted at older audiences. Eventually, with the advent of cable, entire networks would be created for specific audiences. All because programmers know who is watching when and how much.
Television ratings begin with the sample.
The sampling home is recruited for two years and the sample is staggered so about 300 homes enter and leave each month. Sampling technique is constantly refined so the sample of 5000 best reflects the composition of America as determined by the United States Census and other government organizations. The sampling is so sophisticated that each People Meter represents about 20,000 people. From that small sample comes out television ratings. This sample represents the television viewing habits over 270,000,000 Americans.