Nielsen Television Index The source of national and network TV audience information is the Nielsen Media Research, which provides daily and weekly estimates of TV viewing and national sponsored network and major cable program audiences. For more than 50 years, Nielsen provided this information using a two-pronged system consisting of a national sample of metered households along with a separate sample of diary households. In the metered households, an electronic measurement device known as the audimeter (audience meter) was hooked up to the TV set to continuously measure the channels to which the set was tuned. Network viewing for the country (the famous Nielsen ratings) was based on the results provided by audimeters placed in a national sample of homes carefully selected to represent the population of U.S. households. The metered households were supported by a separate panel of households that recorded viewing information in diaries. Since the audimeter could measure only the channel to which the set was tuned, the diary panel was used to gather demographic data on the viewing audience. For many years, the television and advertising industries expressed concern over the audimeter/diary system. The information from diaries was not available to the network and advertising analysts for several weeks, and studies indicated the method was overstating the size of some key demographic audiences. Cooperation rates among diary keepers declined, and often the person who kept a household’s diary did not note what other family members watched when he or she wasn’t home. The complex new video environment and explosion in viewing options also made it difficult for diary keepers to maintain accurate viewing records.
As a result of these problems, and in response to competitive pressure from an audience measurement company from England, AGB, in 1987 Nielsen made the people meter the sole basis of its national rating system and eliminated the use of the diary panel.