ANNOUNCER: CNN viewer David Carroll wants to ask</s>CNN: "How are the TV Nielson ratings determined? Specifically, when and how are the ratings calculated?"</s>BRAD JOHNSON, DEPUTY EDITOR, "ADVERTISING AGE": Nielsen ratings come from three sources. One is the Nielson national ratings that come from a people meter. This is a gizmo that is installed voluntarily in some 5,000 households. And it monitors, with permission, who is watching what, when. The other two forms are local Nielson ratings, and allows Nielson to monitor what that set was being watched, although we don't know who in the family was watching. The final form is the good old Nielson diary. Nielson sends some 1.6 million of these out a year. Around 3:00 p.m. each afternoon, Nielson releases the people meter -- talk about demographics, what women were watching, what age groups were watching. And that is the Nielson ratings.
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