How many readers does Slate really have?

Inside the Internet.
Feb. 27 2006 4:32 PM

Slate Has 8 Million Readers, Honest

Or maybe it's 4 million. Which should you believe?

Illustration by Mark Alan Stamaty.
Click image to expand.

Madea's Family Reunion took first place at the weekend box office, racking up $30,250,000. No one sat down and counted the money, of course. The seemingly meticulous numbers are just estimates. Likewise for Lost's Nielsen ratings, Howard Stern's Arbitron scores, and Beyoncé's No. 1 spot on Billboard's Hot 100. All these are educated guesses, but executives believe in the figures enough to hire and fire over them. Fox canceled Arrested Development because of its low Nielsens, while Madea's Family Reunion 2 has probably been greenlighted already.

There's only one media-ratings system no one takes seriously: Web site rankings. You never see Harvey Weinstein on Entertainment Tonight telling viewers not to believe the latest box-office tallies. But confront any Internet mogul with the numbers published by the two big Web ratings houses, Nielsen/NetRatings and comScore Media Metrix, and you're in for an earful about how they're wrong, wrong, wrong.

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Web publishers are so confident about this because they have their own numbers. A site's internal log files track every single page served, and to where. When publishers compare these internal counts against third-party ratings, they usually conclude that Nielsen and comScore's official rankings are too low. If nothing else, the two companies are often way out of sync. My fellow Slate scribe Adam L. Penenberg pondered this "fuzzy math" last year. Nielsen measured Wired News' audience at 1.096 million, while comScore reported an equally precise-sounding 1.87 million. Which was right, Penenberg wondered—1 million, 2 million, or neither?

It's obvious why nobody trusts site rankings—the "official" numbers from Nielsen and comScore are often so far apart that you couldn't trust them even if you wanted to. But site owners have a real stake in these numbers. Advertisers use them to decide where to spend their budgets, and the inconsistent counts make buyers wary. So, if Web moguls think the published statistics are inaccurate, why don't they just release their own numbers? They will—if you're a prospective advertiser on the phone. Otherwise, they prefer to keep house stats under wraps because they see them as competitive info.

Slate's publisher Cliff Sloan has given me permission to share the numbers from our internal traffic report for December. (Slate licenses software from IBM that compiles monthly, weekly, and daily traffic reports.) The chart below, which compares Slate's numbers to those from Nielsen and comScore, shows two different metrics for looking at site traffic:

Page views are the number of individual Web pages the site served. If one person reads a three-page story, that's three page views. If you reload or revisit the page later, that's another page view. Publishers use this number to measure available inventory for advertisers, who typically pay based on how many times their ads will be shown.

Unique visitors are the number of people who looked at the site. If you look at the Slatehome page at home and at work, that counts as two page views but only one unique visitor. Publishers use this number to give advertisers an idea of the site's "reach"—that is, how many people might see an ad.

Nielsen and comScore agree on Slate's audience for the month, but the rest of the measurements are far apart.

 Nielsen//NetRatingscomScore Media MetrixSlate internal report
Unique Visitors4,600,0004,609,0008,051,709 unique browsers
pageviews40,900,00027,000,00061,089,137

Why the different numbers? For one thing, Slate's 8 million browsers came from all over the world. Nielsen and comScore count only U.S. visitors, the ones most of our advertisers are trying to reach.

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