Early reports Thursday about Huffington Post surpassing The New York Times website in traffic illustrate a critical oversimplification: unique visitors do not equal page views.

The two indicators often trend in the same direction, but not always. In fact, during the month of May after the death of Osama bin Laden, when many news websites reported record traffic -- measured in page views -- the top news sites had fewer unique visitors than they did during the previous month of April (see chart below), based on one set of comScore numbers.

That's not necessarily surprising. Sites can drop in uniques and simultaneously drop in page views. Or, visitors hungry for information about the terrorist leader's death may have consumed more news during a single visit than they typically do (hence lower uniques, higher page views). It's also possible that news magazine sites like Slate and The Atlantic benefited more from a bin Laden bump than commodity news sites, if readers were looking for analysis and context.

Huffington Post and The New York Times increased uniques in May, according to both sets of comScore numbers I received. That could be particularly good news for the Times, post paywall.

There's also an important consideration beyond the raw number of unique visitors to a site: loyalty. What percent of visits come from "addicts" and what percent from casual users, particularly during breaking news? (More important for news sites, how many casual users discover your site during breaking news then stay to become addicted users?)

Quantcast estimates show that three-quarters of visits to NYTimes.com come from 15 percent of visitors described as "addicts." A majority of visitors to the site (51 percent) are regulars. At Huffington Post, the majority of visitors (65 percent) are "passers-by," while the majority of visits are from regulars. Only 1 percent of visitors to HuffingtonPost.com are "addicts," according to Quantcast's direct measurement of the site.

The loyalty differences have important business implications, especially to The New York Times, which has an additional measure -- and benefit -- of loyalty: paid digital subscribers.

For another day: This "competition" between HuffPo and the NYT is a false one, whether comparing the size of the "newsrooms" (which does not simply equal the number of employees) or the size of their audiences. The question is not: Who is winning? The question is: What are their respective roles in the news ecosystem and why does that matter to their audiences and to journalism?

Here's a comparison of unique visitors for March, April and May (I'm awaiting a figure for AOL News uniques):

News site May Uniques (000) April Uniques (000) March Uniques (000)
Yahoo! News Network 73,000 88,000 87,000
CNN Network 64,000 76,000 80,000
MSNBC 45,000 51,000 54,000
AOL News ? 40,000 47,000
The New York Times Brand 34,000 33,000 38,000
Huffington Post 36,000 30,000 31,000