is a very large sample in statistical terms, and the data returned from them includes the viewing preferences of some 11500 people. It has proved to be extremely reliable over the years.
To ensure that the BARB viewing panel is representative of the viewing audience BARB carries out what it calls an establishment survey. The survey is ongoing, and involves over 50,000 interviews a year.
The fact that your friends and family may have similar viewing preferences to yours isn't remarkable, in fact it's probably the norm. That's the reason BARB makes sure that its panel members are selected from as wide a range of socio-economic groups as possible, and also ensures that the panel is represented in all areas of the country. The viewing habits of people of all ages and both sexes are monitored.