Thread: How does the Televisoin ratings system work?

How does the Nielson ratings system work? Like how do these rating compaines know if 3.4 million people actually watched the TV show? Does it work based on number of TV's turned on? Because I could be at a bar or at home and have 10 people at my house watch a tv show or not. So how exactly does it work?

Only a group of people of maybe 10,000 are given a set top box to plug into their TV and record which station their are watching, then they estimate the ratings that the average audience may be wathing based on the 10,000 people polled