David Martin's—Vice President, Primary Research, Nielsen Online—response to Twitter defendants after the original presentation of "Twitter Quitter" research.

Less than a month ago, the kid from That 70's Show made headlines when he beat “the most trusted name in news” to a popularity contest on the micro-blogging site, Twitter. Dispite growing at a rapid—or shall I say BLISTERING—pace, it appears that Twitter has finally found its Achilles heel: user retention. 

Nielsen Research recently pointed out that although Twitter volume has been up triple digit percentiles, its user base typically stays around for less than a month after they sign up. Currently, more than 60 percent of U.S. Twitter users fail to return the following month; meaning the percentage of a given month’s users who come back the following month is currently about 40 percent. For most of the past 12 months (pre-Oprah), Twitter has languished below 30 percent retention.

This is troubling because it signals that although Twitter is all the rage, more users quit the service than stay. Oddly this has been okay because even at 40 percent retention, more inquisitive new users stay each month than the total that left last month. However, as Nielsen also points out, this model is not sustainable—just check out the chart below. By plotting the minimum retention rates for different Internet audience sizes, it is clear that a retention rate of 40 percent will limit a site’s growth to about a 10 percent reach figure. To be clear, a high retention rate doesn’t guarantee a massive audience, but it is a prerequisite. There simply aren’t enough new users to make up for defecting ones after a certain point.

In defense of those who swear by the micro-blogging community, it does merit mention that Twitter is a yet-to-mature social networking space that will inevitably evolve—the maturation of digital-native generations, improved mobile devices, the evolution of the Twitter itself and society's general acceptance of digital social technologies could all reverse this trend. However, compare Twitter's retention to the other two behemoths of social networking during the same time period in their own corporate evolution; Nielson found that even when Facebook and MySpace were emerging networks like Twitter is now, their retention rates were twice as high. When they went through their explosive growth phases, that retention only went up, and both sit at nearly 70 percent today.