> Nielsen is the best-known (possibly only?) company that does this in the US, and they're very good at what they do. Their use of a sample is perfectly fine, a

> Nielsen is the best-known (possibly only?) company that does this in the US, and they're very good at what they do. Their use of a sample is perfectly fine, and there might even be grounds to argue that it's more accurate than trying to get a complete count of viewership. Sorry, but this isn't true. We've known for a long time that their ratings are BS: https://en.wikipedia.org/wiki/Nielsen_ratings#Criticism_of_ratings_systems https://en.wikipedia.org/wiki/Nielsen_ratings#Criticism_of_r... Your other point is true though: They can only attempt to track who is watching ads, not actually track.