One of five (19%) US internet users now uses Twitter or another status-update service, according to an Oct. 21, 2009, article from the Pew Internet & American Life Project. This figure marks a big jump in Twitter usage over the 11% found in two previous Pew surveys, one from April 2009 and the other from December 2008.

Three groups—people who use social networks, those who access the internet via a mobile device, and younger internet users (under 44 years old)—account for most of the increase in Twitter use, say the article's authors, Susannah Fox, Kathryn Zickuhr, and Aaron Smith:

Social Network Users

Some 35% of internet users who use social network sites such as MySpace, Facebook or, LinkedIn also use Twitter (35%), compared with just 6% of internet users who do not use social network sites. Those who use social networks account for 47% of all internet users, according to September 2009 data collected by the Pew Internet & American Life Project.

Statistical analysis of data from the Pew's Internet Project's September 2009 survey reveals that the use of social networks predicts Twitter use, independent of social networkers' relative youth or propensity to access the internet via a mobile device:

Mobile Internet Users

As of September 2009, 54% of US internet users access the Web via a wireless connection from a laptop, cell phone, game console, or other mobile device. One in four (25%) wireless users uses Twitter or another similar service; in December 2008, only 14% did. Among internet users who rely on a tethered connection, 8% use Twitter, up from 6% in December 2008:

Statistical analysis of data from the Pew's Internet Project's September 2009 survey reveals that wireless access predicts Twitter use, independent of the fact that mobile users tend to be young and tech-savvy.

The more devices a person owns, the more likely it is that she or he will use a status-update service such as Twitter. Some 39% of people who have four or more internet-connected devices (e.g., laptop, cell phone, game console, or Kindle) use Twitter, compared with 28% of internet users who have three devices, 19% of those with two, and 10% of internet users with just one:

Younger Internet Users

Age is strong, independent predictor for use of Twitter and other status-updating services. Internet users ages18 to 44 report much faster adoption of Twitter over the last nine months compared with the adoption rate of internet users ages 45+. Some 37% of internet users ages 18 to 24 use Twitter or another service, up from 19% in December 2008.

The median age of a Twitter user is 31, which has remained stable over the past year. The median age for a MySpace user is now 26, down from 27 in May 2008, and the median age for LinkedIn is now 39, down from 40. Facebook, however, is graying a bit: the median age for this social network site is now 33, up from 26 in May 2008.

More

Because social network updates feed into Twitter and vice versa, tracking the use of status-update services will become more difficult over time, say the article's authors. For now, they say, "it is clear that a "social segment" of internet users is flocking to both social network sites and status-update services. This segment is likely to grow as ever more internet users adopt mobile devices as a primary means of going online."

Some findings from other researchers:

• comScore's ongoing surveys of internet users and real-time network data capture confirm the findings presented here: In the previous 12 months, Twitter traffic has exploded, going from about two million to more 17 million UVs from December 2008 to over 17 million in May 2009.
• Harvard Business School researchers analyzed a random sample of 300,000 Twitter accounts and found that "the top 10% of prolific Twitter users accounted for over 90% of tweets."
• Sysomos analyzed 11.5 million Twitter accounts and found that most people post just once per day (and one in five have never posted).

About the data: See the graphics in this article for survey information.