Nielsen recently sent out an explanation of different ratings (metered market, fast national, viewers, households), which you may find being used in a variety of ways by TV propagandists. The explanation is posted after the jump.
As the 2008-09 broadcast television season begins, it’s time to offer some important definitions and reminders about television program ratings.
For the 2008-09 season there are 114,500,000 television households in the U.S. That means that nationally each household rating point represents 1,145,000 households – or 1% of the total. There are 289,950,000 Persons aged 2 and older living in television households, with each Persons 2+ rating point representing 2,899,500 viewers.
A number of different program ratings are released daily to The Nielsen Company’s media research clients. They differ in important ways, as described here, and should be correctly identified in stories.
Metered Market Overnight Ratings: This is normally the first available ratings information, and is based on the electronic measurement service that Nielsen provides in 56 of the nation’s largest markets. In each market a sample of homes is selected to represent that individual market. Often, networks or syndicators provide metered market information as an early indicator of a program’s performance. In aggregate, the 56 metered markets represent 79,890,610 homes, or 70% of all U.S. TV households. Preliminary metered market data are available as early as 8:00AM (ET). Final metered market information, reflecting line-up changes, pre-emptions and runovers, are normally available by 3:30PM (ET).
Fast Affiliate Ratings: These first national ratings, including demographics, are available at approximately 11 AM (ET) the day after telecast, and are released to subscribing customers daily. These data, from the National People Meter sample, are strictly time-period information, based on the normal broadcast network feed, and include all programming on the affiliated stations, sometimes including network programming, sometimes not. The figures may include stations that did not air the entire network feed, as well as local news breaks or cutaways for local coverage or other programming. Fast Affiliate ratings are not useful for live programs, because the data reflect normal broadcast feed patterns. For example, with a World Series game, Fast Affiliate Ratings would include whatever aired from 8-11PM on affiliates in the Pacific Time Zone, following the live football game, but not game coverage that begins at 5PM PT. The same would be true of Presidential debates as well as live award shows and breaking news reports.
Fast National Ratings: These audience estimates, including demographics, are based on the National People Meter sample, and are produced only when subscribing customers request them. These national estimates are based on station line-ups and program times, as supplied by the originating network. Data are based on actual viewing minutes of the program, rather than a straight time period. The line-up of stations has not been electronically verified by Nielsen, however, nor have conflicts been checked. When requested, these ratings are usually delivered early in the afternoon.
Normal Delivery of National Preliminary Ratings: The normal release of prime time viewing information from the National People Meter sample occurs at approximately 4 PM (ET) and consists of household and demographic viewing information based on program times and station line-ups that have been electronically verified and conflict-checked by Nielsen. This means that only audiences to those affiliates carrying the network’s programs are included. Audience information for Monday through Thursday primetime is delivered the next day at 4 PM. Friday’s national data is delivered on Monday afternoon, and viewing information from Saturday and Sunday primetime is available at approximately 8:00 AM (ET) Tuesday morning.
Time Shifted Viewing – Program ratings for national sources are produced in three streams of data – Live, Live + Same Day and Live + 7 Day. Time shifted figures account for incremental viewing that takes place with DVRs which are currently in approximately 24.4% of all U.S. TV households. Live + Same Day include viewing during the same broadcast day as the original telecast, with a cut-off of 3:00AM local time when meters transmit daily viewing to Nielsen for processing. Live+ 7 Day ratings include incremental viewing that takes place during the 7 days following a telecast