Arbitron

Nielsen Audio

Type	Subsidiary
Industry	Media market (research)
Founded	Washington, D.C. (1949)
Headquarters	Columbia, Maryland
Area served	United States
Key people	Sean Creamer, CEO
Products	Ratings data
Revenue	US$422.31 million(FY 2010)
Operating income	US$85.11 million (FY 2010)
Net income	US$53.29 million (FY 2010)
Total assets	US$238.96 million (FY 2010)
Total equity	US$126.81 million (FY 2010)
Owner	The Nielsen Company
Number of employees	1,625 (Dec 2011)
Website	www.nielsen.com/audio

Nielsen Audio (formerly Arbitron) is a consumer research company in the United States that collects listener data on radio broadcasting audiences. It was founded as the American Research Bureau by Jim Seiler in 1949 and became national by merging with Los Angeles-based Coffin, Cooper, and Clay in the early 1950s. The company's initial business was the collection of broadcast television ratings.

The company changed its name to Arbitron in the mid‑1960s, the namesake of the Arbitron System, a centralized statistical computer with leased lines to viewers' homes to monitor their activity. Deployed in New York City, it gave instant ratings data on what people were watching. A reporting board lit up to indicate which homes were listening to which broadcasts.

On December 18, 2012, The Nielsen Company announced that it would acquire Arbitron, its only competitor, for US$1.26 billion. The acquisition closed on September 30, 2013, and the company was re-branded as Nielsen Audio. As a condition of the deal to allow a monopoly, Nielsen must license its ratings data and technology to a third party for eight years.

Arbitron's syndicated radio ratings service collects data by selecting a random sample of a population throughout the United States, primarily in 294 metropolitan areas, using a paper diary service 2‑4 times a year and the Portable People Meter (PPM) electronic audience measurement service 365 days a year.

The term commonly used in the radio industry for these ratings is Arbitron book, a carryover from the era when ratings were published in a softcover report that was mailed to clients. More specifically, in the diary-measured markets these reports were called the "Spring book", "Summer book", "Fall book", and "Winter book". Between these "books", Arbitron releases interim monthly reports called "Arbitrends", which contain data from the previous three months known as "rolling average" reports. The two interim reports would be known, for example, as "Spring, Phase I" and "Spring, Phase II".