|This article's factual accuracy may be compromised due to out-of-date information. (April 2013)|
Nielsen ratings are the audience measurement systems developed by the Nielsen Company, in an effort to determine the audience size and composition of television programming in the United States. Nielsen Media Research was founded by Arthur Nielsen, who was a market analyst whose career had begun in the 1920s with brand advertising analysis and expanded into radio market analysis during the 1930s, culminating in Nielsen ratings of radio programming, which was meant to provide statistics as to the markets of radio shows. In 1950, Nielsen moved to television, developing a ratings system using the methods he and his company had developed for radio. That method has since become the primary source of audience measurement information in the television industry around the world.
Measuring ratings 
Nielsen television ratings are gathered in one of two ways:
- Viewer "diaries", in which a target audience self-records its viewing or listening habits. By targeting various demographics, the assembled statistical models provide a rendering of the audiences of any given show, network, and programming hour.
- A more technologically sophisticated system uses Set Meters, which are small devices connected to televisions in selected homes. These devices gather the viewing habits of the home and transmit the information nightly to Nielsen through a "Home Unit" connected to a phone line. The technology-based home unit system is meant to allow market researchers to study television viewing habits on a minute to minute basis, seeing the exact moment viewers change channels or turn off their TV. In addition to set meters, individual viewer reporting devices, such as people meters, have allowed the company to separate household viewing information into various demographic groups, but so far Nielsen has refused to change its distribution of data of ethnic groups into subgroups, which could give more targeted information to networks and advertisers.
Changing systems of viewing have impacted Nielsen's methods of market research. In 2005, Nielsen began measuring the usage of digital video recordings such as TiVo. Initial results indicate that time-shifted viewing will have a significant impact on television ratings. The networks are not yet figuring these new results into their ad rates due to the resistance of advertisers.
The most commonly cited Nielsen results are reported in two measurements: ratings points and share, usually reported as: "ratings points/share". As of August 27, 2012, there are an estimated 114.2 million television households in the United States, a drop of nearly 500,000 from the previous year. A single national ratings point represents one percent of the total number, or 1,142,000 households for the 2012–13 season. Nielsen re-estimates the number of TV-equipped households each August for the upcoming television season.
Share is the percentage of television sets in use tuned to the program. For example, Nielsen may report a show as receiving a 9.2/15 during its broadcast, meaning that on average 9.2 percent of all television-equipped households were tuned in to that program at any given moment, while 15 percent of households watching TV were tuned into that program during this time slot. The difference between rating and share is that a rating reflects the percentage of the total population of televisions tuned to a particular program while share reflects the percentage of televisions actually in use.
Because ratings are based on samples, it is possible for shows to get 0.0 rating, despite having an audience; the CNBC talk show McEnroe was one notable example. Another example is The CW Television Network show, CW Now, which received two 0.0 ratings in the same season.
Nielsen Media Research also provides statistics on specific demographics as advertising rates are influenced by such factors as age, gender, race, economic class, and area. Younger viewers are considered more attractive for many products, whereas in some cases older and wealthier audiences are desired, or female audiences are desired over males.
In general, the number of viewers within the 18–49 age range is more important than the total number of viewers. According to Advertising Age, during the 2007–08 season, Grey's Anatomy was able to charge $419,000 per commercial, compared to only $248,000 for a commercial during CSI, despite CSI having almost five million more viewers on average. Due to its strength in young demos, Friends was able to charge almost three times as much for a commercial as Murder, She Wrote, even though the two series had similar total viewer numbers during the seasons they were on the air together. Glee and The Office drew fewer total viewers than NCIS during the 2009–10 season, but earned an average of $272,694 and $213,617 respectively, compared to $150,708 for NCIS.
Commercial ratings 
Nielsen also provides viewership data calculated as the average viewership for only the commercial time within the program. This "Commercial Ratings" first became available on May 31, 2007. Additionally, Nielsen provides different "streams" of this data in order to take into consideration delayed viewing (DVR) data, at any interval up to seven days. C3 was the metric launched in 2007. C3 refers to the ratings for average commercial minutes in live programming plus three days of digital video recorder playback. By the end of 2012, some TV executives wanted to see C7, ratings for live plus seven days, with Les Moonves of CBS making the claim C7 made ratings increase by 30 percent.
Electronic metering technology is the heart of the Nielsen ratings process. Two types of meters are used: set meters capture what channel is being tuned, while People Meters go a step further and gather information about who is watching in addition to the channel tuned.
Diaries are also used to collect viewing information from sample homes in many television markets in the United States, and smaller markets are measured by paper diaries only. Each year Nielsen processes approximately two million paper diaries from households across the country, for the months of November, February, May, and July—also known as the "sweeps" rating periods. Seven-day diaries (or eight-day diaries in homes with DVRs) are mailed to homes to keep a tally of what is watched on each television set and by whom. Over the course of a sweeps period, diaries are mailed to a new panel of homes each week. At the end of the month, all of the viewing data from the individual weeks is aggregated.
This local viewing information provides a basis for program scheduling and advertising decisions for local television stations, cable systems, and advertisers.
In some of the mid-size markets, diaries provide viewer information for up to three additional “sweeps” months (October, January, and March).
Nielsen sweeps periods Season November February May July 2009–2010 29 October – 25 November 2009 4 February – 3 March 2010 29 April – 26 May 2010 1–28 July 2010 2010–2011 28 October – 24 November 2010 3 February – 2 March 2011 28 April – 25 May 2011 30 June – 27 July 2011 2011–2012 27 October – 23 November 2011 2–29 February 2012 26 April – 23 May 2012 28 June – 25 July 2012 2012–2013 25 October – 21 November 2012 31 January–27 February 2013 25 April – 22 May 2013 27 June – 24 July 2013
Criticism of ratings systems 
There is some public critique regarding accuracy and potential bias within Nielsen's rating system, including some concerns that the Nielsen ratings system is rapidly becoming outdated due to new technology like smartphones, DVRs, tablet computers, and Internet viewing. In June 2006, however, Nielsen announced a plan to revamp its entire methodology to include all types of media viewing in its sample.
Since viewers are aware of being part of the Nielsen sample, it can lead to response bias in recording and viewing habits. Audience counts gathered by the self-reporting diary methodology are sometimes higher than those gathered by the electronic meters which eliminate any response bias. This trend seems to be more common for news programming and popular prime time programming. Also, daytime viewing and late night viewing tend to be under-reported by the diary.[clarification needed]
Another criticism of the measuring system itself is that it fails the most important criterion of a sample: it is not random in the statistical sense of the word. A small fraction of the population is selected and only those that actually accept are used as the sample size. In many local areas of the 1990s, the difference between a rating that kept a show on the air and one that would cancel it was so small as to be statistically insignificant, and yet the show that just happened to get the higher rating would survive. And yet in 2009 of the 114,500,000 U.S. television households only 25,000 total American households (0.02183% of the total) participated in the Nielsen daily metered system  In addition, the Nielsen ratings encouraged a strong push for demographic measurements. This caused problems with multiple TV households or households where viewers would enter the simpler codes (usually their child's) raising serious questions to the quality of the demographic data. The situation further deteriorated as the popularity of cable TV expanded the number of viewable networks to the point that the margin of error has increased due to the sampling sizes being too small. Compounding matters is the fact that of the sample data that is collected, advertisers will not pay for time shifted (recorded for replay at a different time) programs, rendering the 'raw' numbers useless.[dated info]
A related criticism of the Nielsen ratings system is its lack of a system for measuring television audiences in environments outside the home, such as college dormitories, transport terminals, bars, jails, and other public places where television is frequently viewed, often by large numbers of people in a common setting. In 2005,[dated info] Nielsen announced plans to incorporate viewing by away-from-home college students into its sample. Internet TV viewing is another rapidly growing market for which Nielsen Ratings fail to account for viewers. Apple iTunes, Hulu, YouTube, and some of the networks' own websites (e.g., ABC.com, CBS.com) provide full-length web-based programming, either subscription-based or ad-supported. Though web sites can already track popularity of a site and the referring page, they can't track viewer demographics. To both track this and expand their market research offerings, Nielsen purchased NetRatings in 2007. However, noted in a February 2012 New York Times article the computer and mobile streams of a show are counted separately from the standard TV versions further degrading the over all quality of the sampling data. As a result there was no way for NBC to tell if there was any overlap between the roughly 111.3 million standard TV viewers and 2.1 million live stream viewers the Super Bowl.
After Nielsen took over the contract for producing data on Irish advertising in 2009, agencies said that they were "disastrous" and claimed that the information produced by them is too inaccurate to be trusted by them or their clients.
In 2004, News Corporation retained the services of public relations firm Glover Park to launch a campaign aimed at delaying Nielsen's plan to replace its aging household electronic data collection methodology in larger local markets with its newer electronic People Meter system. The advocates in the public relations campaign charged that data derived from the newer People Meter system represented a bias toward underreporting minority viewing, which could lead to a de facto discrimination in employment against minority actors and writers. However, Nielsen countered the campaign by revealing its sample composition counts. According to Nielsen Media Research's sample composition counts, as of November 2004[update], nationwide, African American Households using People Meters represented 6.7% of the Nielsen sample, compared to 6.0% in the general population. Latino Households represent 5.7% of the Nielsen sample, compared to 5.0% in the general population. By October 2006, News Corp. and Nielsen settled, with Nielsen agreeing to spend an additional $50 million to ensure that minority viewing was not being underreported by the new electronic people meter system.
In 2011, CBS and Nielsen proposed a model consisting of six viewer segments which according to their empirical research are more relevant for advertisers than older models based on sex and age. The segments are based on user behavior, motivations, and psychographics. It is argued that the model can increase reaching the desired audience as well as message recall and advertisement likeability.
Top-rated programs 
The program with the all-time highest average rating is in bold text
Sports programs have italicized rating numbers
Two or more programs tie for highest average Nielsen rating in the same season
||This article needs additional citations for verification. (April 2013)|
- Levin, Gary (2006-10-12). "Playback time for Nielsens". USA Today. p. 1D.
- "Nielsen Cuts 500,000 U.S. TV Homes on Census, Web Viewing". 2012-09-25. Retrieved 2012-12-07.
- Baker, Frank (2009-02-12). "What is a RATING". Media Literacy Clearinghouse. Retrieved 2009-03-02.
- de Moraes, Lisa (2004-08-13). "Where's the Love? CNBC Scrambles to Woo Viewers for 'McEnroe'". The Washington Post. Retrieved 2007-06-08.
- Storey, Michael (2009-04-23). "THE TV COLUMN: Not in 18–49 age group? TV execs write you off". Arkansas Democrat Gazette. Retrieved 2008-05-02.
- Carter, Bill (April 6, 2010). "An ‘Idol’ Ratings Loss, but Not in Its Pocketbook". The New York Times. Retrieved April 8, 2010.
- Santiago, Rosario (2007-10-03). "For Advertising Purposes, 'Grey's Anatomy' May Well be Colored Green". BuddyTV. Retrieved 2009-05-03.
- Steinberg, Brian (October 18, 2010). "Simon Who? 'Idol' Spots Still Priciest in Prime Time". Advertising Age. Retrieved October 28, 2010.
- Holmeys, Gary (2006-01-16). "Nielsen Announces Schedule And Plan For Commercial-Minute Ratings". Retrieved 2007-07-02.[dead link]
- Lafayette, Jon (2007-10-07). "Commercial Ratings Shuffle the Deck". Retrieved 2008-05-13.
- Crupi, Anthony (2012-11-14). "C3POh No! Broadcasters Agitate for Better Ratings Currency". AdWeek. Retrieved 2013-04-09.
- "Neilsen "Sweeps" Months". 2012. Retrieved 2012-12-04.
- "Can You Believe TV Ratings?". Nova / Horizon. 1992-02-18. PBS.
- Segal, Andrea (2007-04-26). "Nielsen Ratings: An Inaccurate Truth". The Cornell Daily Sun. Retrieved 2008-01-19.
- Herrman, John (2011-01-31). "Why Nielsen Ratings Are Inaccurate, and Why They'll Stay That Way". Splitsider. Retrieved 2012-04-28.
- Levin, Gary (2007-04-25). "Networks' top shows at a rating Loss". USA Today. p. 1D.
- "Briefing: Nielsen to purchase all NetRatings shares". International Herald Tribune. 2007-02-05. Retrieved 2008-10-10.
- Brian, Stelter (2012-02-08). "Youths Are Watching, but Less Often on TV". New York Times.
- Noonan, Laura (2010-02-04). "Media agencies losing trust in Nielsen for supply of critical data". Independent.ie. Retrieved 2011-06-17.
- Learmonth, Michael (2006-10-26). "Rupe ends Nielsen tiff". Retrieved 2009-04-20.(subscription required)
- Jack Neff, CBS: Viewers' Age and Sex Shouldn't Matter to Marketers, March 23, 2011, Advertising Age, http://adage.com/article/mediaworks/cbs-viewers-age-sex-matter-marketers/149534/
- McNeil, Alex (1996). Total Television, 4th ed. New York: Penguin. pp. 1143–1161. ISBN 0-14-024916-8.
- "2003-04 Season To Date Program Rankings from September 22, 2003 Through May 30, 2004". ABC Medianet. 2004-06-02. Archived from the original on 2007-02-08. Retrieved 2006-11-24.
- Brooks, Tim and Earle Marsh (2007). The Complete Directory to Prime Time Network and Cable TV Shows, 1946-Present, p. 1679-1698. ISBN 978-0-345-49773-4
- Andreeva, Nellie (May 27, 2011). "Full 2010-11 Season Series Rankers". Deadline Hollywood. Retrieved May 27, 2011.
Further reading 
- Anthony Bianco and Ronald Grover. "How Nielsen Stood Up to Murdoch" BusinessWeek. September 20, 2004.
- Nielsen Media Research website
- Nielsen Media: FAQs – About the "Sweeps"
- Slate: How Does "Sweeps" Week Work? (February 16, 2004)
- Nielsen Global Technology and Information Center website
- Information on Nielsen's Anytime Anywhere Media Measurement Initiative.