Arbitron had been investing heavily to expand overseas, but decided the benefits of merging with Nielsen outweighed the cost of building a global infrastructure on its own, he said.
"For Arbitron, the biggest positive is that Nielsen is a truly global company," Moore said.
For Nielsen, the deal offers new avenues for growth by giving it access to even more information about consumers' habits that can be sold to advertisers, Zgutowicz said. Nielsen's revenue had been plateauing, he added.
The boards of both companies have approved the deal. Analysts said they don't anticipate any roadblocks to the antitrust review.
"Both companies are dominant players in their respective markets, but they are two very different markets," Moore said. "I don't think it changes the competitive landscape for either."
The companies did not say when the deal would close.
In the past year, Nielsen has made some acquisitions of companies that measure consumers' television viewership through social media, so Zgutowicz called this move into the more traditional medium of radio unexpected.
Nielsen reported that it earned $329 million on $5.5 billion in revenue for the 12 months ended Sept. 30. Arbitron made a $58 million profit on $445 million in revenue for the same period.
This is not the first deal between Nielsen and Arbitron. They jointly own Scarborough Research, which gauges shopping patterns, media usage such as newspaper readership and other consumer activity.
Arbitron and Nielsen have been tracking consumer behavior for decades.
In more than 200 markets, Arbitron has consumers jot down their radio listening in a paper diary. In top radio markets, Arbitron uses a Portable People Meter that the company developed. The device is about the size of a pager and passively measures radio listening habits and TV viewership outside the home.
Nielsen tracks viewership with a TV meter and, during the so-called "sweeps" weeks, also has viewers report their TV watching in diaries.
TV and radio stations use the data to set advertising rates.