Nielsen Media Research collects audience data from about 10,000 People Meters placed in randomly selected households and measures 210 smaller markets through viewer diaries during the "sweeps" periods. Customers include TV networks, advertisers, and TV stations. The top media researcher in the US, Nielsen Media makes up the bulk of the media measurement division of parent Nielsen (formerly VNU). It also collects data on Internet use through an alliance with NetRatings (also owned by Nielsen). Nielsen Media plans to also begin providing ratings for TV commercials.
