How do networks know how many people were watching a particular program like a soccer match or american idol?
Nielsen Television Ratings statistics are gathered in two ways: one is by extensive use of surveys, where viewers in various demographics are asked to keep a written record (called a diary) of the television programming they watch throughout the day and evening. The other is by the use of a limited number of Set Meters, which are small computers connected to all the televisions in a home. These devices electronically record the viewing activities of panelists and transmit these records nightly to Nielsen. These Set Meters allow market researchers to study television viewing habits on a minute to minute basis, seeing the exact moment viewers change channels or turn off their TV. Additional use of direct reporting devices (called People Meters) allow the company to break out household viewing information into various demographic groups.
