A.C. Nielsen Ratings Service - The Nielsen ratings compiled by A.C. Nielsen are based on information gathered from 1200 sample households nationwide. A small electronic device called an audimeter (a.k.a. "the little black box") is attached to participating television sets and measured whether the TV set was turned on and which channel was tuned in. Viewing preference information is then fed through special phone lines to the Nielsen computer which records and tabulates the minute-to-minute viewing habits of these sample American families and then distributes the information to the wire services, advertisers, and other parties interested in the television industry. Each point on this survey represents 874,000 households. Beginning September 1, 1987, the traditional "Audimeter" devices were replaced by The People Meter, a more-complex machine used to determine additional viewing factors such as sex and age. On People Meters, a button must be punched before viewing, with separate buttons for parents, children and even visitors. A.C. Nielsen first began compiling national TV ratings in 1950. The People Meter is now the main data collection device used to determine national ratings. The A.C. Nielsen Service was founded in 1923 by Arthur C. Nielsen, Sr. (died in 1980). It is located at 1290 Avenue of the Americas in New York, NY 10104. See also - "Arbitron Rating Service" and "Rating Services"