So what, there is a sample number of houses who have a magic box and then the TV people use this to get an average?
Ratings of Shows Page 2
Basically, lols.
Can't explain it down to a tee (Check out the BARB website), but each selected household (can't remember how many there are now) has a box or device fitted to each TV, video/dvd or whatever in the house and when the equipment is in use it takes a record of what's being watched and for how long.
If 1 person is watching the TV then they have to input that information into the device and if second/third/fourth (etc) person enters the room they have to put that information in as well, as well as telling it wen someone leaves the room as well.
I've always seen it as dodgy, I think that if there were 20,000 panel members(households) and only 5,000 were watching, say, The Bill then it could mean that the other 60 million plus people in the country that aren't panel members are also watching it but only 5,000 households are recorded as doing so.
Not sure how they work the averages out though.