David Martin, Vice President, Primary Research / Sue MacDonald, Research Manager

You've probably heard of the Morgan Stanley report that declares "teenagers do not use Twitter," based on a sample size of one 15 year-old intern named Matthew Robson. Morgan Stanley rightfully disclosed that they do not claim that his study is representational or merits statistical accuracy, so we thought we could provide both with our NetRatings panel of 250,000 U.S. Internet users.

Twitter's footprint has expanded impressively in the first half of 2009, reaching 10.7 percent of all active Internet users in June. Perhaps even more impressively, this growth has come despite a lack of widespread adoption by children, teens, and young adults. In June 2009, only 16 percent of Twitter.com website users were under the age of 25. Bear in mind persons under 25 make up nearly one quarter of the active US Internet universe, which means that Twitter.com effectively under-indexes on the youth market by 36 percent.

While the metrics in the chart above only represent the website and branded "front door" of Twitter, it would be a big stretch to assume that the gap in the youth demographic is being made up via other clients and platforms. For example, more than 90 percent of popular Twitter client Tweetdeck's audience is over 25.  Furthermore, Twitter.com’s reach is 6.6 percent for kids, teens and young adults, whereas it is 12.1 percent for those over 25; implying that adults are trying Twitter at nearly double the rate.

But does it really matter if the kids don't get it? The fact remains that Twitter has grown to be a major online presence and is being driven forward by significant buzz. To illustrate this point: the volume of Twitter mentions on blogs, message boards and forums has reached the same level as Facebook, a property four times its size. We've also seen that Twitter's growth is very highly influenced by buzz around current events such as the Iran election. All it takes is one celebrity or major news story to rekindle the Twitter buzz machine, but do these one-off shifts create one-tme curiosity seekers or lead to more permanent users?  That's the unanswered question.