How do Networks Know How Many People are Watching a TV Program?

Tricia Christensen
Tricia Christensen

Although different regions can use various methods, the traditional way to monitor television viewing habits has been a rating system. In many countries, including the US, the Nielsen Company uses in-house devices that track the viewing habits of thousands of people. These numbers represent what average people of a certain age and gender watch, which then indicates the number of viewers who probably watch a particular show. Networks use this information to gauge how popular certain shows are, which determines how much they charge companies to advertise during those programs.

The television viewing habits of a sample of households are tracked to estimate total viewers of network programs.
The television viewing habits of a sample of households are tracked to estimate total viewers of network programs.

The Nielsen Company

The Nielsen Company tracks what shows viewers watch on television networks through a representative sampling of about 25,000 households that let the company record what programs they watch. This is a fairly small sampling, considering US households with televisions for the 2010-2011 viewing season was estimated at almost 116 million, but they choose people based on their ability to represent varied populations. For example, Nielsen might choose a household with adults and children of multiple genders and age groups to better represent more viewers.

Nielsen Company uses in-home devices to track the viewing habits of thousands of people daily.
Nielsen Company uses in-home devices to track the viewing habits of thousands of people daily.

How the Information Is Gathered

Every time someone in a Nielsen household turns on a television, he or she indicates which person it is and the box tracks how long the person watches a show. Each member of a household has his or her viewing habits recorded individually, through indicating who is watching the television at any given time. If multiple people, including guests, view a program, each one enters information about his or her age and gender into the box so that the viewing habits of each person can be tracked. This viewer-specific data sets the information Nielsen records apart from data gathered by a regular cable television box.

Researcher Nielsen turns samples of viewers into a percentage representing total TV viewership.
Researcher Nielsen turns samples of viewers into a percentage representing total TV viewership.


Nielsen turns this sample of viewers into a percentage representing total viewership. If 2,500 people in Nielsen households watch Example News Show in a week, for example, then they conclude that 10% of television viewers in all households watched the show. This would indicate a rating of 10 points, and networks rank their shows based on the number of viewers they have each week.

The Nielsen box tracks viewing habits by age and gender.
The Nielsen box tracks viewing habits by age and gender.

Demographics and Commercial Ratings

More important than just the ratings of a show are certain demographics and "commercial ratings" for a program. Since the Nielsen box tracks viewing habits by age and gender, companies can specifically target certain groups, such as people between the ages of 18-49. This age range tends to buy more products than other ages, so it has become the most important demographic to many advertisers. Networks can charge more money to advertisers placing commercials in a show with high numbers of viewers in this demographic, even if the show's overall ratings are lower than another program more popular among older or younger audiences.

The Nielsen Company has also established a secondary rating called "commercial rating," which is based on viewing habits of commercials. Ratings have value to networks because they use these numbers to sell time to advertisers. Commercial ratings indicate whether people are actually watching commercials, or simply skipping them through recorded programs or channel-changing. Many advertisers care more about commercial ratings than general ratings or market shares, since viewers who skip their commercials are not as valuable to them as those who watch the ads.

Sweeps Months

Many TV viewers have heard the term "sweeps" related to ratings. During the months of November, February, May, and July, Nielsen sends viewing diaries to millions of households. People keep a manual record of what shows they watch and then send this information back to the company. Networks often run especially exciting programming to attract more viewers during these months, which boosts their numbers in the collected diaries.

Time-Shifted Viewing and Internet Television

One major issue that has arisen for ratings systems is the increased popularity of Digital Video Recorders (DVRs) that let people record shows and watch them later, called "time-shifted viewing." The Nielsen ratings do take these viewers into consideration, but they cannot track exactly what shows are watched at what time, only that viewers recorded them and likely watched them within about three days. Since many people skip commercials during playback on DVRs, many advertisers do not care much about these numbers.

The increased availability of shows on the Internet has offered new possibilities for tracking viewing habits. Television networks can easily see how many people pay for and download a show through various websites, and many of them offer shows for free with limited advertising. The number of downloads can be recorded by television networks and might influence decisions about keeping certain programs airing. Many advertisers do not consider such viewing as valuable as regular TV watching, however, which has made Internet streams for shows less financially important than traditional broadcasting.

During sweeps months, Nielsen viewers keep manual records of what shows they watch.
During sweeps months, Nielsen viewers keep manual records of what shows they watch.
Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent EasyTechJunkie contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

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Discussion Comments


I wonder why no one has complained about the insurance companies and their millions of dollars spent on commercials, but not lowering our rates. Any comments?


I'm 63 years old and I can't remember buying anything as a result of watching a television commercial. Also if a commercial is too loud, I either put the set on mute or change the channel, and if commercials last more the five minutes I fall asleep and end up not watching anything.


They can turn on and off any cable box in this high tech world. The computer system keeps track of all data coming out of the box. They can not just guess from 5000 hillbillies who participated in research and think this represents society!


So does this work with recorded programs, as the TV unit does not even need to be operational while recording programs and then the life giving commercials would simply be fast forwarded by the viewer?


I think the (sad) takeaway here is that tv networks don't care at all about what shows their viewers want to see and how popular a show really is. Rather, ratings are all about advertising and making money.


I wish they would poll the networks I won't watch because of the volume of ridiculous commercials.


I don't think the ratings are accurate representation of actual viewers. The sampling is too small. They don't take into account the many ways people are watching shows.

For example, I work and have children so I don't have time to watch TV shows when they air. I DVR some, but I don't watch them until I have time which could be weeks later. I watch a few via the web and my cell phone. I also watch some via my Sprint TV. I'm a little ticked today because one of my favorite shows, Nikita, is being canceled due to low ratings -- inaccurate ratings. The current ratings system is too antiquated.


Personally, I feel because they use such a small number of "samplings" to determine what is being watched, that this system is unfair. There are likely many shows that had a lot more viewers that were not part of that sampling that got canceled. Humans are creatures of habit for the most part. Because of this, a show could survive solely on a few highly watched (samplings) episodes.


Our household does not pay for TV anymore. We bought an antennae about three years ago. We use a Roku and pay for Netflix and Hulu Plus.

We often wish someone was watching our viewing habits so that "Good Morning America" would notice that we change the channel every time Nancy Grace comes on!


So, If a network paid off a Nielsen employee for access to the list, or a portion of the list of 5000, then contacted and offered some of these participants a few hundred or thousand bucks to tune into a show of their choosing, they could get the ratings to get the advertisers to get massive amounts of money. If I can think of this on the fly in the time it took me to read this article, I'm sure this has been at least attempted.


To the commenter who thinks Nielsen doesn't exist anymore. It definitely does. My parents (both 60+ to the commenter saying they only go to 18-50) are a Nielsen household.

Every TV has a little box attached to it (that they come and spend hours attaching to the internal workings of the TV) that you sign into every time you watch TV. After inactivity (sleeping) of about 40 minutes you have to hit the button to say you are still there. It's a giant pain in the butt and honestly, half the time, you just try to ignore it. So really it's an awful system. They also did the handwritten diary system years ago


I remember when the first generation home video games and VCRs became available the local NBC channel suddenly became extremely popular. Nobody could explain why all of these marginal programs like "Manimal" were getting such high ratings. Finally someone at Nielsen realized that many people were tuning their television sets to channel 3 so they could play their VCRs and video games, not actually watch the shows. Channel 3 just happened to be our local NBC affiliate, so the ratings results were totally bogus.


Okay, the information on this page is a little misleading. I’m not sure that Nielsen is even around anymore. Let alone the 5,000 people thing.

I did not check to see, but if they are then it’s simply either for “show” or for “old-times-sake.” Take a look at that “box” on top of or around your T.V. Even the box that they give you to put in a second room, for a second T.V. that they give you for “free” is exactly for this purpose: Each and every box installed now has its own IP address. So, when you turn on your set and watch a program they can now track you in real time!! I personally think that it’s a gross invasion of everyone’s privacy but what can you do?

I like “anon149803” idea and just download, but you can be tracked that way as well. I guess P2P is the only anonymous way to download and watch your favorite show without being tracked, traced and data based. Welcome to the 21st century where not only you are watching but everything that you do is watched. Flipped that on us didn't they?


There should be like a rating thing on all networks so people can actually rate the show themselves. It would be more accurate and people would get more shows they like aired.


This is just wrong They only use ages 18 - 49. retired people that have worked all their lives and supported the advertisers do not count in this world.


All television broadcasting is beginning to sound like a bunch of poop. Why isn't anything fair these days? I choose not to pay for something I don't want and if the shows get worse, I am disconnecting TV all together and sticking with internet music or Facebook.


True. Getting recorded data of only 5,000 people? I don't think it can accurately represent the actual numbers. There are lots of people, who just like switching between channels to see whatever interests them the most at that particular time. Especially shift workers probably won't have a fixed viewing time or show.


Notice it is never 100 percent accurate and it never will be it is only a guess, nothing more. all the data is made to reflect what they want it to reflect. Next year it will be 115 million viewers. The numbers always favor the intended purpose so Nielsen makes money and the networks make money.


It's all about capitalism. The networks aren't in the entertainment business; they are in the business of making money. Period.

I don't have cable or satellite. I have an over-the-air antenna which receives one local station (two many hills between me and the broadcast sites) so I watch the majority of my programs a day later over the Internet, which I stream from my computer to my TV via PlayStation. That works for me, and it gripes me no end that a small sampling of people is representative of the way I watch TV and some of the best shows out there suffer short air lives because of misleading ratings. Statistically, statistics are bogus!


Thanks for this information, i was searching too many days. You have really cleared my mind about this topic.


DirecTV and Dish network require a phone line or internet connection be plugged into their boxes. They get real time data on who's watching what. They do it anonymously unless you opt into full disclosure but I'm sure the companies along with major cable companies sell your info to advertisers and ratings companies. The nielsen crap is dated and is taking into consideration but is not the only way they find out who watched what. Cable companies do the same thing since they went to digital. Your cable box sends a signal back to the host and requests the channel you want to view. They know what you're watching, when and how many tv's.


It's all based on statistics. And believe it or not, it is pretty accurate. Usually between +/- 3 percent. The sample size would have to grow exponentially above 5000 to decrease the deviation by even 1 percent. In most circumstances a sample size of 5000 is considered extremely large. Most people assume they represent the majority when in most cases they do not.


Not just 5,000 people, but 5,000 people who are actually watching TV. What about the 5,000 not watching TV?


It's not a good system. Logically, a lot of people would not be willing to have their viewing habits monitored. They would represent a distinct portion of the population.

I love sci fi, as do lots of my friends, and we would be more likely to watch online and would also be less likely to let people record our viewing habits.

Right away, you lose a large portion of the population that watches sci fi, so that type of program, for example, will never receive a just assessment.


Tracking 5,000 people out of hundreds of millions seems like the resulting data wouldn't be accurate. I've always been suspect of Neilsen ratings.... But I guess they would argue that they scientifically choose those 5,000 to truly represent what millions of people actually watch....

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