The Ratings Mirage

Reporting on the ratings rivalry between the Fox News Channel (FNC) and CNN is often misleading -- and almost always over-hyped.

"Fox Tops CNN as Choice for Cable News," declared one typical headline in the Chicago Tribune. "Fox News Channel Continues to Crush CNN," reported Knight Ridder in a column comparing the rivalry to a party primary titled, "Fox News Channel is winning the Nielsen caucuses." Last August, the New York Times Magazine declared, looking back at the period of the Iraq invasion, "Fox was -- and still is -- trouncing CNN in the ratings."

After exposure to countless similar stories published since January 2002, when Fox was reported to have surpassed CNN in the Nielsen ratings, one might naturally conclude that Fox has more viewers than CNN.

But it's not true. On any given day, more people typically tune to CNN than to Fox.

So what are the media reports talking about?

With few exceptions, stories about the media business report a single number for ratings (often expressed two different ways -- as "points" or "share"). This number is often presented as if it were the result of a popularity contest or a democratic vote. But it is actually the average number of viewers watching a station or a show in a typical minute, based on Nielsen Media Research's monitoring of thousands of households.

The average is arrived at by counting viewers every minute. Heavy viewers -- those who tune in to a station and linger there -- have a greater impact, as they can be counted multiple times as they watch throughout the day.

When an outlet reports that CNN is trailing Fox, they are almost invariably using this average tally, which Fox has been winning for the past two years. For the year 2003, Nielsen's average daily ratings show Fox beating CNN 1.02 million viewers to 665,000.

But there is another important number collected by Nielsen (though only made available to the firm's clients) that tells another story. This is the "cume" or the cumulative total number of viewers who watch a channel for at least six minutes during a given day. Unlike the average ratings number the media usually report, this number gives the same weight to the light viewer, who tunes in for a brief time, as it does to the heavy viewer.

How can CNN have more total viewers when Fox has such a commanding lead in average viewers? Conventional industry wisdom is that CNN viewers tune in briefly to catch up on news and headlines, while Fox viewers watch longer for the opinion and personality-driven programming. Because the smaller total number of Fox viewers are watching more hours, they show up in the ratings as a higher average number of viewers.

CNN regularly claims a cume of about 20 percent higher than that of Fox. For instance, in April 2003, during the height of the fighting in Iraq, CNN's cume was significantly higher than Fox's: 105 million viewers tuned into CNN compared to 86 million for Fox. But in the same period, the ratings reported by most media outlets had Fox in the lead, with an average of 3.5 million viewers to CNN's 2.2 million.

Even among Fox's core audience of conservatives, CNN has an edge in total viewership. A study by the ad agency Carat USA found that 37 percent of viewers who call themselves "very conservative" watch CNN in the course of a week, while only 32 percent tune to Fox.

Show Me the Money

Journalists who publish Nielsen numbers ought to explain that the data are not simply measures of popularity, and they are not produced as a service to journalists or the public. The figures are gathered to provide advertisers with complex data about viewer habits. It pays to remember that neither cable news stations nor Nielsen Media Research are primarily in the business of serving the public interest -- both are in the business of delivering audiences to advertisers.