How do people know how many viewers a TV show has?

Question

For example on the entertainment section of the yahoo page it says 17.2 viewers watched high school musical. how do they know you where watching it or not? do they have a tracker on your TV?

Answer 1

some families have a box that keeps track of what they watch. it's called the Nielsen rating system. it's a sample that represents everyone.

Answer 2

It's all best guess and extrapolation. The Nielson ratings system counts a small set of stereotypical households and what they watch in real-time. They then extrapolate the numbers (through averages and scaling) to 'guess' that there were that many millions of viewers. Until we have a way to for real-time viewing statistics, it's all still done with averages and extrapolation using small numbers of viewers.

So, each single Nielson household could account for between 1000-10000 viewers (or more) in a given ratings period (depending on how many Nielson households are active during that period).

For Nielson households, they do put a real-time viewing tracker into the home. So, when that home changes the channel, Nielson is informed of that event and what they were watching during that period. Nielson may also use surveys after-the-fact to help validate their numbers.

The last thing I should mention is that Nielson TV ratings chooses the households at random. As such, you cannot request to become part of their TV ratings households.

For TV/Media ratings:
http://www.nielsenmedia.com/nc/portal/site/Public/

For Internet Surveys:
http://www.nielsen-netratings.com/

Answer 3

The number comes from the nielson raings. Households are selected from all over the country and tracking boxes are put on their TVs. The numbers are reported from those boxes and then estimated for the rest of the country based on demographics.

Answer 4

People are randomly selected across the country according to socioeconomic breakdowns to either have their sets monitored or to have written diaries kept. The records are evaluated and ratio-ed up to the entire nation. If the ratings come out the next day, you know that the sets are monitored electronically.