What are ratings in media?

In the U.S., the term "TV ratings" is synonymous with "Nielsen" because Nielsen Media Research has become the de facto national measurement service for the television industry. Nielsen measures the number of people watching television shows and makes its data available to television and cable networks, advertisers, and the media. The company has been measuring television audiences since 1950, when TV sets were just beginning to appear in many households.

TV ratings provide valuable insights into how many people are consuming content, as well as how and when they do so. That information is useful for advertisers, networks, and other entities in the media industry that make content or market products and services.

Since it's a tall feat to measure the viewing habits of every single person in the U.S., Nielsen uses a technique called statistical sampling to rate shows. It's the same technique that pollsters use to predict the outcome of elections. Nielsen recruits people to join its TV ratings panels and measures what they watch, how often they watch it, and how long they watch it. Nielsen then extrapolates the data that it collects from these sample audiences to draw conclusions about larger populations. That's a simple way of explaining a complicated, extensive process.

Around 20,000 households are included in the representative sample for the national ratings estimates. Though this number is a small percentage of the 121 million homes with TVs in the U.S., panels are selected so that they mirror the makeup and behavior of the larger populations that they represent.

Panelists are strategically selected. They provide Nielsen with information about their gender, household income, and ethnicity. To measure how panelists watch TV, Nielsen uses a combination of panel data, data from cable and satellite set top boxes, and census data from digital devices (collected through measurement tags in content). Meters installed on panelists' TVs track who is watching television and what they're watching. The meters send reports of panelists' TV viewing to Nielsen, and they collect information from signals from TV broadcasts. To ensure reasonably accurate results, Nielsen uses audits and quality checks and regularly compares the ratings it gets from different samples and measurement methods.

The media landscape has changed dramatically since the mid-20th century. Viewers can watch TV programming on many different devices, and Nielsen ratings have had to adapt to new playing fields. For instance, the company measures live, DVR, on-demand, and streamed content.

In recent years, Nielsen has introduced initiatives to reckon with the reign of video on demand and streaming services. In April 2021, it launched Nielsen Streaming Video Ratings, acknowledging the shift in viewers' preferences. But its ratings still do not account for viewership outside of the U.S., and its streaming metrics only measure what people are watching on television screens. Considering the trend toward more streaming on phones, laptops, and other devices, traditional methodologies for TV ratings could quickly become outdated.

Still, media research is worth billions of dollars. Advertisers pay to air their commercials on TV programs using rates that are based on Nielsen's data. Programmers also use Nielsen's data to decide which shows to keep and which to cancel. The technology may be scrambling to keep up with the rapidly changing landscape, but the industry continues to rely on TV ratings for decision-making purposes and bragging rights.

Originally Published: Jul 28, 2000

OzTAM is the official source of television audience measurement for the five mainland metropolitan markets in Australia – Sydney, Melbourne, Brisbane, Adelaide and Perth – and nationally for subscription TV. 

OzTAM TV ratings are audience estimates that are based on actual viewing behaviour of 5,250 homes in Australian metro cities. The homes provide a representative sample of the Australian population and when the TV in these homes is switched on, the meter lights up and asks who is watching. Viewers log in and out when they enter or leave the room and the meter gauges all TVs within the home.

Click here to learn more about OzTAM.

RegionalTAM is the ratings provider for television audience measured in regional Australia. RegionalTAM represents panel homes in Queensland, Northern NSW, Southern NSW, Victoria, Tasmania and Western Australia. There are currently 3,198 homes (Queensland 812, Northern NSW 700, Southern NSW 570, Victoria 651, Tasmania 285 and Regional West Australia 180) representing a potential audience of 7,859,300 individuals. 

Click here to learn more about RegionalTAM.

Ratings are a measurement of how many viewers are tuning in to a television show. The ratings are used to set advertising rates for television networks, determine the network's schedule, and even the content of the shows. Basically, to a network executive, ratings are everything.

Ratings are usually reported as points and shares. A ratings point is 1% of the market's total amount of households with televisions, meaning that for a national broadcast in the United States a ratings point is equivalent to 1,128,000 households. A share is the percentage of televisions on at the time that were tuned to that program. So a show with a "9.2/15" was watched by 9.2% of households with television, and 15% of households with televisions that were actually on at the time. For instance, the farewell episode of M*A*S*H had an astounding 60.2/77. It is possible to get a 0.0 rating and still have viewers. That just means that an insignificant number of the sample households were watching that show (or at least nobody actually being monitored for statistical data was watching). This is known in the industry as a "scratch", as a double quotation mark is printed in the ratings report to show that a ratings number could not be computed.

Besides the number of viewers, ratings companies also record the type of viewer, or demographics. In the US and forty other countries ratings and demographics are compiled by Nielsen Media Research, so sometimes the ratings are referred to as "Nielsens".

Besides automatic meters installed in some homes, the ratings companies will send out diaries to homes and pay people to accurately write down what they watch. These periods are called Sweeps, because the diaries used to be sent out to one region of the country and then the next, "sweeping" across the country. (Or, one could argue, this is the period where the networks want to "sweep" as many viewers to their offerings as possible.) More recently, ratings companies have made deals with DVR manufacturers like Tivo to use their DVR viewing statistics, which would theoretically increase the accuracy of the statistical data by increasing the size of the statistical data pool (as well as theoretically decreasing bias by shrinking the "visibility" of data collection). It's also probable that networks also look at stream numbers for episodes on their websites and Hulu, though these numbers haven't really been disseminated as broadcast ratings for advertisements remain the main metric for measurement. Notably, Netflix hasn't really delved very deep into the numbers for their original shows such as House Of Cards and Arrested Development.

Not to be confused with Media Classifications.

In some cases, networks may see ratings as more of a secondary concern. Publicly funded broadcasters such as The BBC in the UK, PBS in the US, or The ABC and SBS in Australia, have charters which they are expected (as public services) to fulfil, irrespective of how this affects their ratings. However, these are by far the exception rather than the rule.

Needless to say, ratings play a very large role in deciding whether a series stays on the air or not. It is quite possible that low ratings were responsible for the death of your favorite shows. To the average viewer or fan, ratings are the bane of their existence and completely throws quality out the window, because audiences just don't usually care about ratings.

A story from the analog days of TV ratings: Until the early 2000s, network executives, reporters and others interested in the previous night’s audience had to make a phone call to get them. 

After a certain time each morning, the overnight ratings would come in from Nielsen, and someone from the network would recite the numbers onto a dedicated line, which then was available for anyone who wanted to dial in and hear how shows performed.

It’s … a little different now.

Those overnight ratings still come each morning (via email, and with more information rolled into them), but they’re followed by a host of other data: three-day, seven-day, multiplatform, commercial. Theoretically, a TV outlet could count the digital audience of its show for as long as it wants. (That notion is, in fact, part of how HBO’s Game of Thrones racked up such eye-popping numbers for its final season. Keep reading.)

Here’s a rundown of the various streams of ratings data, starting with the most basic bit of information.

The Nielsen ratings are calculated based on a sample of 40,000 homes and about 100,000 people that’s demographically representative of the population as a whole. It’s a small fraction of the 120 million or so homes with TV, but also a lot more than, say, a typical political poll that surveys just a couple thousand people.

Rating: Ratings are essentially percentages, measuring the portion of a given group — be it households, adults 18-49 or women 25-54 — watching a given show. Adults 18-49 is the primary demographic by which ad rates are set for entertainment programming, so it’s the most commonly reported (one point in that demo equals 1.28 million people). So a 2.0 rating for The Masked Singer means that 2 percent of people in that age range, roughly 2.56 million people, watched the show.

Share: The percentage of a given group who are watching TV at that time and are tuned into a given program. Wednesday’s Masked Singer had a 10 share in adults 18-49 (10 percent of adults under 50, who had their TVs on at that hour, watched it). It’s typically written as “rating/share,” so 2.0/10 for The Masked Singer.

Total viewers: Pretty self-explanatory — the average number of people watching a program in any given minute while it airs.

Overnight metered market ratings: These are the first ratings released each morning — or they were, anyway, until Oct. 3. Nielsen is planning to include out-of-home viewing in these numbers from now on (the first day of the new system didn’t go well), which means they’ll be released around midday now. Metered market ratings only take measurements from 44 markets (56 previously) for households and 25 markets for adults 18-49, so they’re best considered as a first draft on how programming performed rather than definitive. They had been useful for gauging live events since they measure programs instead of just time periods.

Live-plus-same-day: The ratings that get reported each day, first as “fast nationals” in the morning and then as final numbers in the afternoon. They include both live viewing from the previous night and delayed viewing until 3 a.m. local time. Fast nationals are generally pretty accurate for entertainment programs, with occasional small adjustments in the finals.

Live-plus-3: Same-day ratings with three additional days of DVR and on-demand viewing added in. The majority of delayed viewing that Nielsen measures happens in this timeframe, with most shows growing their audiences by a good amount.

Live-plus-7: The same as live-plus-3, extended to a full week. In the 2018-19 season, two dozen series at least doubled their 18-49 ratings after seven days.

C3 and C7 ratings: Arguably the most important ratings numbers that the public doesn’t usually see. These ratings track the number of viewers who actually watch commercials — which is why Nielsen ratings exist in the first place — over three or seven days. They play a big role in setting rates for advertisers buying commercial time. The occasional glimpses at C3 and C7 ratings in recent years have suggested they’re higher than same-day numbers but a good distance short of live-plus-3 and live-plus-7 numbers.

Live-plus-35: An even longer-tail measurement that takes into account viewing that happens up to five weeks after a show airs. It’s not a huge piece of the viewing pie, but it’s not tiny, either.

Multiplatform ratings: Things can get a bit fuzzy here, as multiplatform ratings can include streaming and digital viewing via a network’s app or third-party service like Hulu, plus on-air replays. The digital audience is growing — some shows get more viewers there than from their on-air showings — but no company in the business willingly offers up definitive streaming or digital viewership. It’s only included as part of a whole. (It is possible to subtract, say live-plus-7 ratings from a multiplatform total to get a rough estimate of how many people watch something via nontraditional platforms).

Furthermore, each network has its own way of calculating cross-platform viewing, and timeframes can get murky. HBO touted a massive audience of 44 million viewers for the final season of Game of Thrones, but that included up six weeks of streaming and replays of the season premiere, five weeks of episode two and so on.

Streaming ratings: Are not really a thing. Nielsen does measure the audience for streaming shows, but Netflix and other platforms have disputed the ratings service’s numbers as they don’t take into account viewing on other devices.

Netflix has reported some viewership figures in recent quarterly earnings reports, but they’re not really analogous to Nielsen ratings. Netflix considers a piece of content as having been “viewed” when a member account watches at least 70 percent of one episode of a series or 70 percent of a feature film. It also counts subscribers around the world rather than just the domestic viewers that Nielsen measures. The numbers can be useful in comparing one Netflix show to another, but the service has thus far only publicly released highlights, not a full tally.

For live events that include a streaming option, networks or other providers will often cite an “average minute audience” for a live stream. That’s the closest thing to Nielsen’s average total viewers statistic.

Social ratings: Nielsen measures social engagement around TV shows, counting the number of posts about a given episode and the reach of the conversation. As with all ratings, higher is better, but heavy social conversation and high on-air ratings don’t necessarily go hand in hand.

Third-party measurements: A number of companies measure things like out-of-home viewing or binge viewing, but they can rely on users to opt in to sharing data, which can lead to a less representative sample.