I believe CNN has a rational rating of news stories that, at the outbreak of story, estimates the number of viewers the story will gather. If it is a “big” story (e.g., the Zimmerman trial), two things happen: (1) the amount of time devoted to the story is adjusted; and (2) the price per advertising minute goes up. Just like airlines have sophisticated algorithms to calculate the optimized price per seat at any given moment, I think CNN and others know exactly how to price their advertising time. The result is tabloid news.
