It's perhaps premature, but Mashable attempts to extract from the early data the impact on visitor stats and pageviews of the New York Times paywall, which went into effect March 28: What Impact Has The New York Times Paywall Had on Traffic?
Premature, because the studied period ended April 9 and many people may have only begun hitting its monthly limit of 20 free stories in recent days.
Experian Hitwise thinks it has the answer to the first question. The research and intelligence firm analyzed traffic data for NYTimes.com from before and after the paywall was erected. According to its data, traffic has declined overall by 5% to 15%.
Hitwise measured the change in total unique visitors between February 22 and March 5 as well as the number of visitors between March 29 and April 9. Overall, it was no contest: unique traffic has dropped since the paywall, with most declines in the 5% to 10% range.
The effects of the NYTimes.com paywall are far more pronounced on the website's total pageviews, though. Using the same time period, Hitwise found that pageviews dropped between 11% and 30% after the paywall was erected.
Pageview drop totally makes sense. I found myself rationing my reading so as not to use up my allotment of 20 free stories, not clicking from the NYT homepage to stories I would earlier have read, thinking this couldn't be a good sign. Sometimes I'd copy a headline and paste it into Google, knowing five more free stories a day were readable that way. This was tedious. Each browser has its own set of counting cookies, so you can switch browsers and start over. But many people only use the browser that came with their computer, and may not know how to get and install another one.
Links from blogs are also uncounted -- we bloggers deliver pageviews, after all.
The Times, in a balancing act aimed at getting revenue while still spreading the news, rewards the tech savvy with free access while charging "the normals." (This gives new meaning to the phrase, "the knowledge economy.")
I was grateful to learn about the many Twitter and RSS feeds that would bypass the paywall -- http://twitter.com/freenyt/firehose, http://nytimesriver.com/, New York Times journalists on Twitter and 7 More Ways To Smash Through The New York Times Paywall.
Or you may prefer to subscribe to unlimited access for $15 a month, $20 for tablets, or to newspaper delivery at various levels, which come with digital access.