Nielsen ratings 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 : 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 . Ratings / share and total viewers . 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 . Demographics . 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 " " , 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 . Sweeps . 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 2 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 ) . 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 smartphone s , 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 . 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 . 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 , 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 viewer impact . 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 , , 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 psychographic s . It is argued that the model can increase reaching the desired audience as well as message recall and advertisement likeability . Top - rated programs . " Main article : List of most watched television broadcasts " This table lists all the TV shows with the highest average household Nielsen rating for each television season .