A media market, broadcast market, media region, designated market area (DMA), Television Market Area (FCC term) or simply market is a region where the population can receive the same (or similar) television and radio station offerings, and may also include other types of media including newspapers and Internet content. They can coincide or overlap with 1 or more metropolitan areas, though rural regions with few significant population centers can also be designated as markets. Conversely, very large metropolitan areas can sometimes be subdivided into multiple segments. Market regions may overlap, meaning that people residing on the edge of one media market may be able to receive content from other nearby markets. They are widely used in audience measurements, which are compiled in the United States by Nielsen Media Research (television) and Arbitron (radio).
Markets are identified by the largest city, which is usually located in the center. However, geography and the fact that some metropolitan areas have large cities separated by some distance can make markets have unusual shapes and result in two, three, or more names being used to identify a single region (such as Wichita-Hutchinson, Kansas; Chico-Redding, California; Albany-Schenectady-Troy, New York; and Harrisburg-Lebanon-Lancaster-York, Pennsylvania).
In North America, radio markets are generally a bit smaller than their television counterparts, as broadcast power restrictions are stricter for radio than TV, and TV reaches further via cable. AM band and FM band radio ratings are sometimes separated, as are broadcast and cable television. Market researchers also subdivide ratings demographically between different age groups, genders, and ethnic backgrounds; as well as psychographically between income levels and other non-physical factors. This information is used by advertisers to determine how to reach a specific audience. In countries such as the United Kingdom, a government body defines the media markets; in countries such as the United States, media regions are defined by a privately held institution, without government status.
A Television Market Area (TMA) is a group of counties in the United States that are covered by a specific group of television stations. The term is used by the U.S. Government's Federal Communications Commission (FCC) to regulate broadcast, cable, and satellite transmissions, according to the Code of Federal Regulations, at 47 CFR § 76.51 and http://www.fcc.gov/oet/info/maps/areas . The TMAs not only delineate local broadcasts, but also delineate which channels will be received by Satellite or Cable subscribers ("must-carry" rules). These market areas can also be used to define restrictions on rebroadcasting of broadcast television signals. Generally speaking, only stations within the same market area can be rebroadcast. The only exception to this rule is the "significantly viewed" list.
A similar term used by Nielsen Media Research is the Designated Market Area (DMA), and they control the trademark on it. DMAs are used by Nielsen Media Research to identify TV stations that best reach an area and attract the most viewers. There are 210 Nielsen DMAs in the United States and 56 metered markets. There are also 210 TMAs regulated by the FCC within the United States (citation needed).
Arbitron at one time also maintained similar areas for television ratings, each called an area of dominant influence (ADI). There were 286 ADI's in the United States. Arbitron no longer offers a television ratings service.
In 2009, Nielsen began offering radio ratings in competition with Arbitron, starting in those markets ranked 101st and smaller.
Canada also has a similar system, run by the Bureau of Broadcast Measurement (BBM).
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