BARB conduct the TV ratings survey. A few thousand households in the country have a little black box attached to each TV in their homes. Every member of the household has a code, and whenever they are in the room watching the tv, they type in their code and the box registers it. The info is sent back to BARB and they then work out how many poeple were likely to be watching. The boxes are spread between all age groups and social groups. So while the majority of those few thousand with the little black boxes might be watching BBC, its possible that the other 59 and a bit million of the population could be watching ITV. In other words the ratings are a load of tosh, a flawed tool no doubt seen as the Holy Grail by Ad men.